I went from a '98 (same bike as '99 basically) to the '03, and I haven't regretted the move at ALL. If you want something faster and MUCH more hardcore and focussed, you will be in heaven. If you want something with a softer edge for longer highway tours, you won't. I personally enjoy twisty roads and occasional track days, and I can't picture a better bike for my needs. If you poll all the guys I ride with, in honesty they'd almost all agree, the ZX636R is king for the kind of riding we do, right there with the Gixxer 750. It seems like more than a 600 (cheater bike) and still, like the Gixxer 750, rides like a 600 when compared to the liter bikes... I think it's the best of both worlds.