I haven't been in a RZR yet, but some friends had them last year. I was quite impressed with how well they did.
One observation was: don't put aftermarket rims on them if they are wider that the origional. You won't fit throuth the 50 inch barriers. One RZR had to turn around on our ride last year because he was about 52 inches wide with his aftermarket rims.
We made that mistake last year with wheels at 54 inches but doors at 56. I had to pay over $300 to get the doors fixed and put my stock wheels back but this year we'll ride whatever we want. It is easy to forget width when getting new wheels, tires and other accessories.