Something like a nine or a 12 has power from 3000rpm rather than starts to get moving at 8000rpm and is screaming at 10000rpm which might be say 110kph in second but not handy in a 30kph corner.
The 600 clas bikes probably wind up quicker if your a lightweight too like under 70kg.
I used to love the 250 up the hills because it all happened at a reasonable speed with a heap of gears and at full throttle.... have you had any 250s go past ya latley strika.

Also depends on the road like the northern end of the putty seemed like it would suit a 600 a whole lot more its a way more open type of twisty but the runoffs didnt look so good.