I prefer the Cat 550 for several reasons. 1 easy to get to the rad. to blow it out 2 easy to get the cap off to check liq. levels 3 more clearence in the rear axels for mud to get out. 4 a bit wider than most giving more side hill stability, much needed. 5 ability to use a rec. hitch.  I have 2 with power steering, that is really nice in my applications where I ride side saddle often or steer with one hand.  Downside like all atv's with boots seems we tear them up too often even though we have boot protectors.  Keep in mind ours are in pastures  all the time, this can mean rad. pluging material.  WE have a 650 with 9000 miles just sold a 550 with 7600 miles new 2012 has 1500 miles and just bought used 2011 with 600 miles had 280 when I bought it in Feb. CVT tranny is nice but does burn more fuel than a manual shift.  Ben