Chris,
There is some division among posters within this forum about the X series machines. Since this is a compact tractor oriented forum by and large, most will favor a compact or subcompact machine to an X series. I am not in that group necessarily, but there are some points to remember.
First, the Yanmar diesel is essentially the same engine in both the 744 and the 2305 sub-compact. It is extremely powerful, fuel-efficient (expect to use about 40% the fuel of the Kawasaki-equipped X series machines for the same work) and very durable. It will likely outlast the tractor itself and is very much worth the money.
Second, any of these smaller machines, including a 2305, would be pushed around a bit by a 647 tiller and hard soil. Adding liquid ballast and wheel weights would really help. It is quite easy to add over 300# of ballast to the rear tires/wheels of the X series machine and it will not move much then. The hydro transmission does have sort of a transbrake effect and is not easy to push around when "disengaged".
Third, this is controversial, the X series machines are just nice. They are expensive and perhaps overpriced in some aspects, but so are Ferraris, and I can tell you I still want one of those cars. The X series tractors are meant for homeowners who mow a lot but need a machine that is comfortable to operate and can do more than just mow. They are 100% American made with the only real outsource being the engine (even the Kansaki transaxle is made in the US) and are in my opinion the top of the lawn and garden food chain. Although I like the X 500 series machines they cannot compare to these. The only problem is that when one starts to upgrade to a rear PTO for tiller, a three point hitch, etc., they start to become cost prohibitive. Many times then it is better to look into the 2305. The only problem I have there (no disrespect to those that own them) is that the 2305 is just not as nice. It is not as comfortable and smooth when mowing, does not steer quite as well, etc. It is a fine and capable machine but not as polished for those homeowner specific tasks. John Deere really did its homework on the X series machines and it shows through. Truly, either purchase direction you consider it might end up being better to just buy new as these machines (X series or 2305) simply do not depreciate enough in my mind to make buying a used one worthwhile in most cases. The MFWD on the 2305 is a nice feature though, but will not hold that tiller back much better than a ballasted X series machine.
Whether you decide to go with more standard features of the 2305 or the high refinement of the X744 becomes a personal choice, but both machines can handle the jobs you mention with no trouble. I also have no heard that the four wheel steer machines offer any significant liability when doing this type work due to ground clearance.
John M