i have an 02 954 and my buddy has a 2000 f4i. when i rode the f4i i felt uncomfortable on it because im a bigger dude and the f4i bunched me up alot. it had a great smooth ride and it handles very wellbut if youre a big guy go for a 954. they are stretched out more and they are just more comfortable for a guy like me. the power is not lacking either on the 954. however it is not a busa, but you will not be disappointed with thepoweror the handling.

 

Either or are great bikes. The 954 is nimble and has tons of power and torque but the F4i is a track weapon. If you love the twisties you're not going to gain much by going with the larger cc bikes. With the bigger bikes you have to get on the throttle later because of the power it want to wheelie out of every corner and the 954 are wheelie happy as all hell. I have a 929 and have contemplated going back to a 600 just because they have more power than I'd ever need not that I don't love my bike.