Stuff I have:
-4500 lb Warn winch with wired remote/roller fairleads - looks nice, only made sure it worked so far, haven't tested it, remote takes up a lot of space in the glove box
-Honda full length roof - Nice but be aware that it "holds water" when it gets wet. If you then go downhill or brake, it dumps cold water into your lap which can be a startling experience the first time it happens.
-Honda front and rear A-Arm guards - Rear is really nice, front really doesn't seem to do much for guarding the CV boots, probably would go aftermarket if I could do it over again
-Molded bed liner - It does cover pretty much the whole bed and it does keep trash from falling into the rear seats and it fits well enough that you can just leave the screws out (I don't think I would trailer it like that though) and you can get it out fairly easily but I don't think it is worth the nearly $300 asking price
I have a Honda rearview mirror that I bought Tuesday that haven't mounted yet but I test drove a unit that had it and I liked it and I will probably wind up getting a glass windshield after it turns off cold, since that was a request from my wife but I want to test it in the cold first, I have a feeling that the seat heat will be more than enough to offset the need for the windshield considering how slowly we usually drive and our relatively mild winters. I also want to get something to expand the on board storage. I don't really like the Honda bag that hangs on the roll bar but it may be my only option right now. I noticed that they make door storage bags for RZRs on a used on at my dealer that would be really nice. Surprisingly, considering the lack of on board storage on the pioneer, I haven't been able to find any specifically for the Pioneer yet though.
Hope this helps.