both are great bikes and I thought I made a mistake when i bought the 450 cus the first 10 hrs i couldnt ride it at all . It tired me out and I couldnt hold on and the suspension was stiff as hell for me.. well this bike comes set up for an expert from factory I had an expert help me set up my bike for me and then at 10 hrs the suspension broke in for me and I started riding like less of a goon. now at 25 hrs I am throwing this thing around a bit and getting on the gas hard. the moral of the story is this bike is fantastic .. I hated the 04 yz 450 my buddy has this has useable power that gets traction instead of spinning every where.Im a 41 yr old sr c rider.. the suspension is fantastic the motor is perfect for me, I put a fmf q pipe on it and actually went up a tooth on the rear so I could turn more in 3rd gear worked great. yesterday I went to a practice day at local trac with 60 other novices and rode 5 hard motos as hard as I could and just had a blast and was able to hold on and push the bike all 5 laps. I am so stoked now.. so get up and go buy one you can handle it..