If you are talking about the rewards, give it at least 6 months, both of them will have more or less the same payout for the last 6 months. Most normal pools have fees which can result in p2pool having more payout. They also have email notifications which alerts the user if the hashrate falls below X.
Is there any reward for the P2Pool owner ?
Some of them run it for free for others. Some people set up their own nodes and mine it on their own node as it have less latency and traffic.
So, unless a P2Pool owner has his own mining equipment, he's not gonna profit from this ...right ? Because, like a normal pool owner, he cant charge ...is not it ?
Unless you impose a fee and people are still interested to join it which is unlikely.
Is it possible at all to impose a fee on mining payout for a P2Pool ?
Yes, if you run this command,
screen -d -m -S btcp2pool ~/p2pool/run_p2pool.py (username) (Bitcoind password)
It will automatically donate a small amount of the miner's revenue to you.