I guess i am the lucky one, mining in CF @ 735kh with default settings.
Definitely! Even though people use the same configuration, each card actually is different. For example, when I was running 3x 7950's at default clocks, each 7950 would give me 582Kh individually, but together - only the first gpu gave me 582Kh, the other two only got 530Kh or so - when running at intensity 18. However, if I bump up the other two cards to intensity 19 each, then all three would give 582Kh. With overclocking, they can get 630Kh without getting two hot, but here in Australia - it is summer, so I don't like the gpu's getting to 90 degrees, so am keeping them under 85 degrees - once we get to winter, I can run them harder.
[Edit] Also, the cgminer version does make a difference - the latest is not always the greatest. I am running 3.7.2 - the last version to support gpu's. I feel that 3.6.6 was giving me slightly better hashing, but am staying with 3.7.2.