I'd say stick to the q6600 as the price the qx9650's go for isn't worth it the small performance increase
I'd stick with the qx9650 and sell the q6600...
So your saying . . . given the choice betwen two processors where the performance difference between them is "small" but one is worth approx £80 and the other is worth approx £165 he should sell the one that is worth less?

So he ends up with a processor that is fast and £80 instead of a processor that is fast and £165?

Seems to be stable. The cooling I am using is a Corsair H50 with 2 files attached so hopefully that is enough.