Well i will throw in my .02 i fully agree with most people on here that say a 600 has more than enough power to enjoy. I on the other hand am not happy with the power a 600 has to offer main reason i have been riding for awile and i have gotta used to the power and cornering capabilities. The bike hasent changed it just takes alot more to get that adrenaline rush you get when you first get on it. I can also chalk it up to the fact that i am 6'3" 300lbs that greatly affects the capabilities on a 600cc bike.
Just my .02

Derek