Well... Isn't share submission somewhat related to time? My computer is running 24/7, so I don't see why I'd get less shares on longer blocks? The front page links to http://forum.bitcoin.org/?topic=1976.msg50002#msg50002, where Slush explains it is a score based system. Are you referring to another link?

I'd be interested in your 6950 configs. As I said, I'm a casual miner, and I mine on my primary rig, so I don't want to push the overdrive too hard (I'm F'ed if I burn it). I'm with -v -w 128. I have one of those new low cost single Bios Saphire 1GB 6950 cards, whose shaders can't be unlocked (at you flash with no safety net). I've pushed the OC up to 840Mhz, where I mine at 330MH/s, with the card @ 79°. Any way to get more bang out of it without pushing the clocks further?