I'm looking at my stats for last 1500 shares for each pool I'm using, and here are the results:
With BTCGuild, it's 16 of 1500,
with DeepBit, it's 6 of 1500,
and with bitcoins.lc it's 40 of 1500.
So it may really depend on the pool.
Two cards run @ 1GHz core/300 MHz RAM, and one runs at @ 950/300. When overclocked too much, they don't increase the rejection rate, but the miner just hangs instead
I noticed that while BTC Guild was undergoing maintenance two weeks ago my stale rate shot up for my Phoenix miner, but not for the Ufasoft miners. As soon as the maintenance was finished the Phoenix stale rate dropped back down to next to nothing with no setting changes on my part.