i have a two buddies with rzr's......
for me the difference was:
legally allowed at our largest riding location (was a big sticking point for me) i could put a car seat in it and take my kids, take my wife, etc....
easier to haul
fits in our tight trails
you sit down in the rzr, good for sport riding
quite a bit less $$
compared to the xtz (stock) it's slower
doesn't have a v-twin....i like the sound of a v twin
can't haul much at all (we have 43 acres and 90% of my use of the prowler will be there)
you sit down in, not easy to get in and out of when you are in a hurry (out on the property with a chainsaw and a string trimmer)
not as roomy
it just depends on what YOU want/are going to do with it.....
there's nothing wrong with a rzr, but it was sure fun when we took off on our first ride this weekend and i ran mine up to 74mph and my buddy's rzr was banging off of the rev limiter at 55mph.....
in some trails my xtz out preformed the rzr and in some trails the rzr out preformed the xtz.....
i was second guessing my purchase but after i've had a good deal of seat time and spent some time playing with the rzr's, i'm confident i made the right decision....