you must have lots of riding experience. to handle the 400 Vinny came across to me he is nervous on riding a 450 and if he is, then he should go to a 250. I am nervous about riding a 450, if i wasnt, it would be no question, i would get the 450. I am very comfortable on my 125, but would just like a little more power, i am very tired of my bike "falling off the pipe" when i hit a small kicker jump before a big jump, then i dont clear it. I am also very used to ringing my bike out, and i have fun doing it, so i think the 250f sounds like a logical choice.