I did not have good luck with the Yard Man I had for two years but it was a lawn tractor, not a garden tractor (I didn't know Yard Man made a true garden tractor). It was a gift from my in-laws when they stopped mowing their own lawn. My tractor was laid up with a bum Kohler Command motor so I was very grateful to have it and it was not too bad to use. It was almost new when I got it and after two years of mowing while dragging my 235 pounds up and down my hills the transmission was shot (not a hydro but one of those that work like one with the forward and reverse pedals and variable drive). The mower deck was literally coming apart in pieces, more than once I found myself with the sawzall chopping off chucks of metal that had broken loose and were hitting the blades. The Briggs 20hp motor was still fine, ran really well and the seat and tires/wheels were still good, that's about it.
I think it really matters who will be using it, what terrain they will be usinig it on and most importantly who will be maintaining it. I do a lot of work around my church too and some of the tools and equipment they have, well I just have to shake my head at they way they are treated. People want to help which is great and they mean well, most of them just don't know any better. I'm big on the theory of pay more for quality now, less for repairs/replacement later. You come out ahead and you get to use a much nicer piece of equipment or tool. When you are talking about equipment that might be abused and/or not maintained properly it becomes hard to decide if the extra cost of quallity will be wasted because it will be trashed anyway or will the extra cost pay off even more becuase it can stand up to the abuse better.
As far as the Cub Cadets someone mentioned, I have heard that the shaft drive on newer ones do not use regular universal joints like the older ones did and they are not nearly as reliable and very expensive to repair. That is just what I heard so take it with a grain of salt, I'm just saying find out before you buy one if you consider a Cub Cadet (and let us know what you find out if you do). With a hydro transmission I don't think there is much stress on the drive belt anyway since it is really just spinning the hydro pump, not trying to drive gears directly connected to the wheels. I have never had an issue with a belt driven hydro, even at 235 pounds going up hills for 13 years. I'm not a mechanic that's just my personal observation.
The price sounds pretty good on that Yard Man though so it's a tough decision. If mine was a heavier duty garden tractor with a beefier, hydro transmission it probably would have held up better. If people use the one you are looking at and maintain it properly it will probably be OK for a few years but I still wouldn't expect to get 10 years from it. Heck, if you only got 5 years from it that's only $320 per year which I don't think is too bad. Anything beyond that is gravy.
I wish you the best of luck and good for you for being willing to help out at your church, that's a blessing to others that you will surely be blessed for too.