http://www.xbitlabs.com/articles/cpu/display/core2quad-q9300_13.html#sect0
I have to disagree with you looking at these facts/trials which prove otherwise in performance and power when comparing the 9300 vs. the 6600 stock vs. stock as well as over-clocked amounts. In terms of over-clocking, even though the 9300 is 100 MHz slower than the 6600 at 3.5 vs. 3.6, the 9300 exceeds in every test. Regardless of the lower cache amount, the 9300 is a far superior chip; the only current drawback is the price, which will soon change, since it is a bit inflated over the $250 suggested retail price.
From the same site: "The benchmark results indicate clearly that all our concerns were absolutely unfounded. Core 2 Quad Q9300 is faster than Core 2 Quad Q6600 even without a larger L2 cache, only thanks to architectural improvements introduced in Penryn processors, higher bus frequency and 100MHz higher clock speed. Moreover, there isn’t a single application where the old CPU would demonstrate higher results, and the overall performance advantage is about 7%, which is quite a lot."