The X7's hit well above their weight, regardless of whether you find a hydrostatic AWD, or an earlier MFWD version. And 1500 hours on a diesel is barely broken in, as long as it hasn't been abused and has been properly maintained. I owned a 2008 X748 SE (last year of the MFWD) for eleven years, bought it new. When I traded it for a 2-series compact, it had 1500 hours on it. Used no oil, PTO clutches operated perfectly, and I had the 540 rear PTO, in addition to the 3-point hitch. I also had a 45 loader. This machine was a worker, not a garage queen lawn mower. I used a 50" rototiller as well as a wood chipper on the rear PTO. I had no issues with the MFWD in terms of usability, and I had R1 tires on it. I mowed 5-6 acres with it, and did quite a bit of landscaping and gardening work.
The mower was a 54C, didn't have, or need, autoconnect. Only took 5 minutes to drop or connect the deck. I also had a PowerFlow and MC519 cart with it. Had I anything to do differently, I would have gotten the 60" 7-Iron deck for it.
Since you already have a larger diesel tractor, I'd definitely look for a diesel X7. You won't be sorry you got one, they are awesome machines.