If ride quality is a major consideration, take a look at Ferris. They build consumer grade as well as full-on commercial ZTR's with independent suspension, coil overs on all four corners. I had a customer that had a big Ferris with a caterpillar diesel. The downside to full suspension, is usually cut quality. As the mower floats up and down, the deck does also.
A quick word on swapping to aggressive tires. I was working as service manager for Deere when the L series mowers came out. With turf tires. We had some customers fit bar tread tires for hillsides, and that's when the trouble started. A piece of equipment will usually have a weak link, that part or feature that will fail before anything else. Oftentimes it's engineered that way, in order to protect more expensive components. Shear pins are a good example, designed to fail, and inexpensive, so the high dollar stuff hopefully survives.
Well it seems that lack of traction, WAS the weak link. Deere knew the transaxles were marginal, but turf tires would slip before internal damage occurred. When lug tires were fitted, they didn't slip as easily, and the NEXT weakest link began to fail. Unfortunately that turned out to be the transaxle itself, and Deere claimed a voided warranty when bar tread tires were installed. Made for some awkward customer relation moments.
I doubt that it would be as much of an issue on a full commercial machine, just something to keep in mind.
