Get the 450X... I'm biased because I have one, but the 450R is pretty sweet too. I like the electric start on mine and the bike is just built a little sturdier.. The X can easily be made to keep up with an R with a few simple mods, airbox, pink-wire, boysen quick shot, and different exhaust.. i've ridden a modded one side by side with my stock X and the difference is like night and day... gobs of rip your arms of torque down low and it revs a lot longer... you'd be happy either way, X or R...! :) just my 2 cents