also I'm pushing a constant 12 MHS at you but it constantly says 9.x - 10 on your site, is that an issue on your side or mine?
My site reports the hashrate obtained from only accepted blocks. But I wouldn't imagine your rejected rate is high enough to cause that.
On my miner, I get 1.4-1.5 MH/s as reported in cgminer, but my site is reporting me at 1.3-1.4. This tends to happen on any pool I go to. The pools report me at around 10% less hashrate than cgminer.
Maybe when cgminer detects a new block from the network, it takes a second to send the new info to the GPU, and anything produced by the GPU in the meantime is wasted. The higher block rate coins would affect this more, and my pool tends to mine those coins. But I'm really not sure. If this is an issue, I might need to include it in my profitability calculation somehow.
Does this happen to you at other pools? Do those pools mine high block rate coins?