We've had our 500 for almost 2 years and nearly 400 hours. It fits our needs well. Would be a great replacement for a golf cart. I've taken ours up some grades that I had no business climbing. Put it in L and lock the diff and hold on. We use ours for hauling square bales, firewood, snow removal (2/3 mile driveway) and general farm chores.
It is NOT a play vehicle. If you're looking for speed and compliant ride, get a midsize ranger, you want a durable work tool, get the rtv500.
As for the HST, do a search and you'll find a couple threads on adjusting the aggressiveness of the HST. We tweaked our throttle stop, pedal travel and HST servo and can climb all but the steepest hills in H. Keep in mind that I live in western PA and we have some nice hills
As others have stated a sucide spinner is a helpful as is a windscreen and roof.