Why do you ride a 600? Do you see it as a stepping stone to a 1000?
I have owned 1000s and I just like 600rr better than any other bike. It is faster than I ever need it to be, and still surprises me if I haven't ridden in a while. Other than bragging rights, which I do not care about, I see no reason to pay more for gas, more for insurance, increase the likelihood of theft, and tempt myself even more to ride at dangerous speeds.
I have owned 1000s and I just like 600rr better than any other bike. It is faster than I ever need it to be, and still surprises me if I haven't ridden in a while. Other than bragging rights, which I do not care about, I see no reason to pay more for gas, more for insurance, increase the likelihood of theft, and tempt myself even more to ride at dangerous speeds.