Ive had an Outlander 800 and HATED it. The visco lock front diff is junk, but it was faster than any other atv I know of. I sat in a Commander for the first time yesterday at Mtn Motorsports, and that thing is nice. The XP is great for wide open trails and tracks, but through the woods and tight race courses the Rzr-S will own an XP, I know because BudgetYJ and myself both race our Rzr-S, and our lap times are significatley faster than the XPs and the Commanders. If it was for trail riding and not Hardcaore wheeling, then Cammander would be better for the price. If you plan to race, rock crawl, or wheel hardcore, then I would buy a base Rzr and get an aftermarket longarm kit. It comes with all the parts you will have to replace anyway, better axles, a-arms, bushings, and shocks.
These are not facts, just my opinions.