i own both an 06 250f and 450f. ergonomics wise, the 250f is a little more tight than the 450f, but neither have a "large" cockpit by any means. i am 6'1", 195 lbs, and lowered pegs made the 450f just right. feel/handling--both bikes feel roughly the same on the dirt or in the air--advantage goes to the 450f in the turning dept...its point and go with no second thoughts...i cannot feel a significant weight advantage to either one... power--no brainer. if you like to bounce the bike of the rev limiter, the 250f will get you wherever you want to go. if you would prefer to throw the bike in third gear, feather the cluth occasionaly, and have power on tap to make up for any/all of your mistakes, then the 450f is the right answer. the 450f gets much more of my seat time than the 250f...its just to easy!