I pay 3% at BTC Guild. I get paid for orphans, I get merged mining with NMC (impossible on p2pool solo), extremely low variance, 0.2% stales, and transaction fees.
You're going to have a hard time convincing me p2pool is better than that.
M
I don't want to convince you, because we value the benefit of mining differently.
Especially the decentralization and variance part.