The issue with p2ppool is ASIC miners will not work on them

https://bitcointalk.org/index.php?topic=90658.0

Hardware latencies

ASICMINER Block Erupter blades: they seem to work correctly according to this post

Avalon: I've ordered one in batch 2 but don't have any experience with it yet... There have been various informations floating around but no definite conclusion. Here is what is reported to influence how Avalon and P2Pool behave, you may want to try different combinations of these suggestions:

• Test different versions of the Avalon firmware, beginning with the latest one.
• Avalons apparently have a limitation with stratum that a new branch of p2pool tries to circumvent: you may want to try this branch
• try to use cgminer's "--fix-protocol" to avoid Stratum
• contact the p2pool devs on the #p2pool IRC channel to report feedback (and maybe get some tips)
• force a high difficulty for the shares submitted by Avalon by adding +n at the end of the username used to connect to P2Pool (try n=16, 32, 64, ...)

Please report your experience (hashrate, DOA and orphan percentages and efficiency) if you can. Current reports are incomplete and seem to indicate that Avalons don't reach 100% of their mining efficiency on P2Pool.

BFL: if you have a BFL Single, an early FPGA MiniRig (cgminer has a parameter for later ones to fix them, check its documentation) don't waste their hashrate on P2Pool, they have huge latencies and can't perform well on P2Pool. Put them on a traditional pool.  If you have a BFL SC (ASIC), ckolivas and kano reported the same problem, see ckolivas post. At least two users reported around 100% efficiency: here and here. You might want to test it for yourself for at least 24h and report your results here (please include the details from cgminer's API if possible).