The only thing I'd add, which may or may not be obvious is...

- A G0 stepping Q6600 at xxxMHz @1.5v very likely runs the same temps as a B3 stepping Q6600 at the same xxxMHz @ the same 1.5v.

...it 'might' run a bit cooler due to some of the lower-voltage-optimizations part of this stepping, but maybe only a few C, if that. The primary factor is still how much voltage you're applying, so the benefit (if any) of the G0 would be:

a. because you don't have to apply so much voltage to get to the same overclock.

b. even if you end up having to apply the same voltage, you have more temperature headroom to work with, which might let you push it higher (or at least stablize an otherwise twitchy overclock).