Not sure if you will see this as it is an older post but I have experience in the areas you are looking at..
We have a 2.5 acre lot. We often cut a neighbor's lot (1.25 acres) so lets call it cutting just under 3 acres of grass by the time you take into account driveways, houses, pole barns outbuildings and uncutable ares. For years I have used a John Deere 2002 X585 that has a 54" deck with the MC519 MCS (PowerFlow head and cart with the casters) and I still have it. Though the X585 is now a dedicated machine for snow duties in the winter and Front End Loader work in Spring, Summer and Fall. I think I have a little over 1200 hrs on the X585. I had some electrical issues and other things that needed mending. It was hard to take it out of commission for several weeks in the summer as I needed it for mowing and even harder in the winter as we never know when it will snow next. So I started looking at options. Whatever I went with I needed a MCS and FEL. That ruled out a new X Series unless I kept the X585 as a dedicated FEL machine. I also didn't want to use the X585 for MCS work because when I am doing fall and spring clean up that is when I use the FEL the most as I manage my compost piles with it. I don't like mowing with the FEL because it raises the center of gravity too much in the ditch and it is too hard to get around the trees. I looked at a 1 Series to maintain a FEL but at the time (2 years ago) the only option for MCS was a 3 bag hopper. I could have gone non John Deere but then couldn't roll it into 0% financing. I also would have the challenge of having one machine for the FEL work while doing that spring and fall cleanup. I looked into a new X739 but didn't really gain much. I would have kept the X585 as dedicated FEL and while 4 wheel steering would help with my trees, it isn't any faster. Then I saw the Z9xx series. The fact that I could do not only a MCS but one that I could dump from the seat without getting off the machine. While the hopper is smaller than the MC519 (I think 14 bushels vs 19 if I recall) the fact that the ground speed is so much higher (12MPH on an R model vs 8MPH) means runs to dump in the back of our lot are quicker and I just flip the dump lever vs getting off the machine. This means it is a time saver even though it means a couple more runs to dump.
So I sat down with the sales guy and we started talking. He originally steered me to a Z915B. My concerns were how much HP does it take to run the PowerFlow head? He said it will sap about 2HP. I like the Kawasaki engine better and was leaning toward a "R" to get the hydrostaic deck lift so I didn't have to adjust the spring tension on the foot assist when I added or removed the PowerFlow head. It also has a higher ground speed (12MPH vs 10 MPH) for those runs to dump as I mentioned. We discussed deck options. I haven't read much good news about the MOD deck. It may depend on what kind of grass you have but look around and you will see lots of complaints about clumping. So I wanted the regular deck in 60". That directed me to a Z950R. It has the power to run a 72" deck but by mating it with a 60" you have enough power to spare to run the PowerFlow head. It turned out that they had a dealer demo of a 2015 Z950R with the Dump From Seat MCS that I wanted sitting outside that they were willing to work with me on the price. It had about 60 hrs on the clock if I remember but this is a home machine so hours didn't mean much to me. I wasn't going to exceed the warranty based on the hour meter. Also it was being sold as a "new machine" in terms of the warranty inception date so I was fine with that. It didn't have the suspension seat that I wanted though. So I was still considering paying a bit more to get the seat I wanted. In negotiating we got the price down to where I wanted with 60mo 0% financing and they threw in the a new suspension seat. SOLD!
As far as the Z950R.
Sure they are maneuverable cutting around trees. With my X585 which is 2 wheel steer and 4WD doesn't have that tight of a turning radius. That meant going around a tree twice. With the Z950 I go around once. The trade off is you will shred the grass leaving dirt around your trees. So smaller trees will probably need a mulch bed if you want it to look good in order to open up that radius. The other part of why they are faster is sure they have a higher ground speed but look at it as a more usable ground speed. By this I mean sure my ZTrak will go 12MPH but I don't cut that fast. Much like with my X585 would go 8MPH but I wouldn't cut that fast as it couldn't keep up. The blades on a ZTrak spin much faster than the blades on my X585 meaning I probably get as good of a cut at 8MPH with the ZTrak as I did at 5MPH with the X585. Can you run it at top speed doing passes, sure, you will have some stragglers but that will depend on how sharp your blades are, grass type and the bigger issue how rough your yard is. That is the other factor. A tractor has an articulating front end. I never thought this improved ride much until you get on a Zero Turn with no suspension and a solid connection from the frame to all wheels. You can get bounced right out of your seat at speed. Then there are other differences. For instance a Zero Turn has casters for front wheels like a shopping cart. The back wheels are used for steering and forward/reverse motion. Sure, you knew that but what does that mean? Well the front wheels on a tractor provide lateral support when cross cutting a hill. Think about running down a ditch cutting the side. Casters don't provide this lateral support. So to maintain a straight line across a hill you have to run it with the nose pointing a bit up hill in a crab direction. Not that big of a deal unless it gets really steep. Then it is hard on the grass. I don't really have that issue. Here is the next issue with hills. Going down them. A Zero Turn can flat out be scary going down a hill. As you go downhill, your weight is transferred to the front casters which have no directional or braking control and off your rear wheels which is where you need traction. This can cause a loss in control going down hill. If you read any operator manual they all say only mow steep hills going up them, then back down keeping your rear wheels lower than the fronts. For the most part my yard isn't that hilly. The one place I have to be really careful is the side of our house. It is a slope (not very steep) down hill going to the front with a retaining wall. I doing like cutting that going up hill because that would discharge clippings on the sidewalk and stairs. So going down hill I am heading for a 3' retaining wall which would hurt if I slid off of and dropped 3' down on the driveway. I take it really slow. The right answer is to build up that 3' wall to a 4' or 5' wall which would level out the ground more. I haven't done that yet but should. Personally I haven't had an issue but I have read where people drive straight down hills carrying too much speed and run into a tree when they realize they can't steer or stop. I have never had any of these issues with my X585. It just means the kids are not going to take over mowing for me anytime soon. Too much risk.
On to the MCS. Overall very happy with it. I agree that they are not very common. Lets face it, the Z9xx is a commercial mower. I know some people in the industry and I asked about John Deere. They seemed to say positive things in general but they said they were kind of expensive and said to look at some other brands as well. eXmark for instance. I explained I liked the 0% for 60mo and the collection system. Everyone said not to get the collection system and that they would never buy one. They all said to mulch. I don't want to mulch that much as I like having the dirt I produce from my compost pile for use around the yard. Then I got thinking about it from their perspective and I explained my thinking to them. We simply have different use cases. For them, they are mobile. So they fill the hopper, what are they going to do with it. They need to find a place to dump it or haul it away. This means another truck with a trailer, more people and more time than if one guy was running a mulching blades. No wonder they don't like them. That isn't my use case. I have a place to dump. It just means making a run at 12MPH to the back yard, flipping the lever and I am done. Sure it adds a bit of time to my overall cutting, but I am just doing my yard and maybe a neighbor. I am not trying to get as many yards cut all day long as possible to make money. We simply have different priorities. As I explained my thoughts they pretty much all agreed that for my use it may be fine. The mechanics of the MCS. The PowerFlow head is much heavier duty compared to the one on my X585 which is the same basic design as the ones today even on the 1 Series. They use a plastic body which will erode away after about 5-7 years use and you are going to have a $200-250 bill in parts to rebuild. The one for the Z9xx is an all steel design. There is a plastic deflector which runs $80 but is really easy to replace. One could probably replace that with a steel one if you are creative. Basically it is designed to run all day everyday and is built to last. In residential use I will probably never wear it out (other than the deflector). With the X585, I have already been through 2 PowerFlow heads and the current one is in need of a rebuild. Since I don't use it for that anymore I am not going to bother. If there is any big complaint with the MCS, it is smaller so it fills faster. I also can't easily tell when it is full. The MC519 has a canvas top (which will wear) so I could reach back and feel when it is full. The DFS MCS on the Z9xx is all hard plastic. I find I either over fill it or dump too early until I get used to how much I can pick up. Since I only use it in the Spring and Fall, it is a learning curve I go through often.
So overall I am happy with my purchase. My comments on what you are thinking. I would consider a Z950M or R over the Z970R. If you are only running a 60" deck I don't see the need for the added HP. I have no problem with HP on mine. Well maybe it bogs down a bit running the MCS if I get into deep pine (White Pine) needles. If you are talking Maple, Ash or Birch leaves, it can't be slowed down. With the 970 you will likely just see higher fuel consumption and not much benefit unless you have a lot of pine. I would be cautious with the MOD deck. There are options for a blocking plate on the normal deck. I just haven't read much positive in reviews on the MOD. In fact I have read of more than one person either trading in a Z9xx for a non MOD after getting it or doing a deck swap. I haven't read of any complaints with the standard 7 Iron Pro deck. Just positive reviews. I would watch getting a deck bigger than 60" if you have uneven ground. For instance cutting those ditch areas. The smaller the deck the better job it does with the uneven ground. My 54" on the X585 cuts it better than the 60" on the Z950R but not enough to make me want to go back. There are quirks with any Zero Turn in dealing with hills. I would recommend checking with the dealer. Most offer on-site demo. Cut your grass before you buy to make sure you don't have any problem areas. You will shred your grass more as you learn. You can't pivot on one wheel and do a 180 deg turn. You need to keep both turning. Better to still do 3 pt turns. With the control sticks it is still way faster turning around than with the foot pedal control and steering wheel even with a knob. Also if you are looking at MCS don't get the Tweels. They look cool but if you dig into the details you will find out the Tweels are not compatible with a ZTrak that has a MCS. I think it is because they max out at 750lbs per wheel. With the Z950R and 60" deck you have to add 252lbs of suitcase weights, plus the bracket. Take off the rear bumper but add the hopper mount and the hopper. Add a full hopper of wet grass clippings and a 250lbs operator and the weight of the machine. You are probably blowing past the 750lbs max rating on the Tweels. Sure they look cool and I could see the justification for a commercial operator in they need to keep the machine moving to make money and have little to no control over broken glass or nails in a yard. That isn't the case for a homeowner. Also the tread will wear out and you are looking at $1000 for new Tweels. If you trade in every few years that is fine but if this is a long term ownership. Stick with traditional tires.
Not sure if this helps at all and it sounds like you already opted to stick with the tractor but maybe it will help you or someone else. Ask if you have other questions in areas I didn't cover.
