What I noticed - and this puzzles me - is that different GPUs in the same rig have wildly different stale rates!
I have one two-card computer with a 7950 and a 7950 in it, and I found the 7970 (in GUiminer scrypt (in reality that's cgminer behind the scenes), intensity 13) to get around 3% stales, whereas the 7950 in the same guiminer instance (bit a separate worker) got nearly 20% stales (intensity 20 - same result on intensity 18).
My results mining on erundook.net's wdcpool2 since last night with my 7970 is 9214 shares accepted and 290 stale, according to guiminer/cgminer, this conforms with the site stats, and my payouts seem to be exactly as expected, too.
So, while I've seen horrible stale rates from other GPUs, and the orphan rate on the pool seems to be around 10%, at least this one 7970 gives me a WDC income that seems to fit well with coinchoose.com.
I thought the different results people were getting were related to network latency or something, but since two cards in the same rig can behave so differently, there must be something else to it. I have no idea what it is, though!
