I just bought an RTV500, and really like it. So far I've used it for some pretty serious work around the ranch, hauling salt to livestock, fencing materials, servicing sprinkler pivots, and dragging an "irripod" system through a rocky pasture (that's another topic, but it sure beats chasing water down a ditch!), weed spraying and general errand running. I tried to get it stuck and couldn't--yet.
The RTV500 is replacing a smaller ATV and a Toyota pickup, and seems to do the jobs those were doing better than the old equipment. I looked at the Ranger and Mule, and also the Gator line. The Ranger is probably a better choice for serious off roading like hunting or trail riding. But the Kubota is just right for around the ranch.
Power is adequate. The hydostatic transmission feels different from a gear or belt driven machine, and will have you wondering at first, but it seems perfectly adequate, though nothing to get excited about.
Kubota is offering 0% for 60 months right now, so the deal was unbeatable. The dealer knocked the price down to $7900. At that price, and the finance offer, there really was no way to justify spending more on the Ranger.
There have been threads about a noise from the alternator. I don't hear it, so they either solved it or mine hasn't started making it yet. Overall, it's pretty quiet.
The only real annoyance is the fuel gage is under the front seat. It hardly uses any fuel, so I tend to not think about it. With the gage hidden, out of sight, out of mind---. I haven't run it out yet, but I'm sure I will. The slope of the hood makes you feel like it is tipping sideways the first few times you drive it. There are a bunch of warning lights on the dash, but in bright sun, it's hard to see if the parking brake light is on or not. If anything important came on, I'm not sure I would be able to see it with the sun hitting the dash.
It crosses small irrigation ditches and big rocks in my fields in 2 wheel drive with no problem. I'm at 7,000 feet, so hp is probably going to be reduced some.
Kubota roof and windshield were ridiculously expensive and the dealer didn't have them anyway. After market is just coming on line for this new model. I'll probably add a roof, not sure about the windshield.
The dealer discouraged me from getting it set up for snow plowing. He said it was too light for the kind of winters we get here.
Overall, I'd recommend it for a serious work machine around the farm or ranch, but probably not for a back country trail machine.