The better question is how much self control do you have. I actually traded out of a GSXR1000 for a GSXR 600 and they were both very fast and very engaging bikes to ride. If you thought you wanted to do some wheelies etc.... I'd say get the 1000, otherwise the 600 is nearly as fast and a slightly lighter and more nimble package. You can't go wrong but my recommendation would be the 600, it will be plenty fast, a lot cheaper to acquire and easier to insure and you'll have just as much fun.