Hey, Im looking at getting a new 2007 bike, definately Yamaha. I currently ride a 2000 426 with a jacked clutch, and a bunch of problems. Im not the fastest rider by any means, probably decently slow by most standards, but I want a bike I can get better on, as the 426 is a lost cause at this point. I am 5'10, ~180lbs. Should I go for a 250f, or a 450f?