My church owns an earlier version of this mower (2006) that seems to be very similar. It's a 26 HP Kohler with hydrostat and a 54" deck. It's had some serious abuse (bent several deck mounting links and a number of mower blades) but has never needed major repair. For about 5 years it mowed 3 to 4 acres, now it regularly mows about 1/2 acre.
The good parts are the engine and the deck. I like the Kohler twin and it has a filter and pressure lubrication. I think it's had one spark plug change in 10 years and that's it. The deck is heavy and has spindles with grease fittings. It seems to have had some hard impacts but the spindles and bearings are original.
The hydrostat is still fully functional. It seems to me to be a bit weaker than it originally was, especially in reverse, but I can't swear to that. No leaks apparent. Other than that it's a typical mower. It's kind of slow and rough riding. It's got a big gas tank and that's good because the Kohler sucks down the gas.