10-20% local reject rates are normal when submitting shares to a p2pool. That will not impact your payout expectation since the rewards are spread proportionally across all miners
AHH! that's awsome! i had no idea! i thought i was just configuring something wrong, i've never messed around with the ability to adjust my own difficulty before, so i thought i was messing that up. I seem to have found a sweet spot, i'm running 1 7970 so about here +0.0058414 is running well... i think, i wish i could tune it further, but i'm assuming it's fine.
i tried that other pool... http://next.afraid.org:8119/static/ and i was getting 30-40% rejects...
so i'm back with yours fenican!