Another problem with p2pool is the fast block times, and the fact that the bitfury chips don't have an option to cancel the job they've started. This means that it would be impossible to avoid large percentage of stale blocks.
I see... no wonder NanoFuries and Drillbit miners also have high dead rate (about 6%), like BFL miners.
But the situation of these Bitfury miners is still better than average dead rate (6.7% in month) of p2pool network.
Maybe because it is a common issue for mining hardwares, though with different causes.