When did you mine in P2Pool? And could it be that the p2pool was lucky With p2pool you will see payments immediately, they're just not mature until 520 blocks. Same here except you start to see them when they are mature. The hashrate for me predicts ~1350 YAC / day. I got yesterday in 21h ~1300 YAC (hashrate was also higher for a while) which sounds about right. Overnight I got another 600 YAC (~9h so again, about right).

17YAC would mean a whole block right now. It was 24 ~day before yesterday and 48 and 94 and ... it's dropped fast, seems to be a function of difficulty.

I guess you need to think how many hours have you been hashing and how many of those have actually been paid out. Right now it seems the lag is ca 7h to get 520 confirms. Also discard first few blocks, their rate will be lower because of PPLNS. And you can look in the transactions. Do your payouts per block look about right considering your hashrate and pool hashrate. Expect the block to be worth about 15-17YAC.