I am shopping 2006 450's and need some input. I am a 25+ and Vet B top 3 racer and have been doing so on a 2005 YZ 250F with all bolt on mods. I'm 6'3" 205 and in decent shape but my job demands do not allow enough time to train during the week anymore. My 250 F is great because I can ride it like a 125 and not get tired, but I am the only one in my class on a small bore. I want to stick with Yamaha but going back to the 450 is more physically demanding. I have been reading that the RMZ does not tire you out becuase the motor is so smooth. My question is: How rideable is the YZ 450 motor for 2006 and are any of you noticing early fatigue due to the power? Also, have any of you ridden a 2006 RMZ 450 in comparison to the 2006 YZ 450? Thanks!