A lot depends upon what style of bike you'll be getting. If you're looking at a sportbike, you'll find the handling much quicker, the brakes touchier and the acceleration a lot quicker than what you'll experience on the course bikes. If you go for a standard bike or even a cruiser, you'll find the handling characteristics familiar but with (usually) more power and better brakes. Whatever bike you purchase, the best thing you can do for yourself is to practice what you'll learn on the course in an empty parking lot to get familiarised with it. Ideally, you should purchase a bike as soon as possible after the course so you can practice the skills while they're fresh in your mind.slider03 wrote:What should I expect the differences to be if I went from the 250s used in the classes to buying a 500 to 750cc?
There's other things to consider apart from handling and performance, such as what purpose the new bike will be used for. Commuting, touring, weekend canyon carving, dual-sport adventures and so on each have their own unique characteristics - a cruiser will not be a good choice to go chasing sportbikes down the Tail Of The Dragon, for example.
Do you have a particular style and make of bike in mind yet?