Check out:
https://bitcointalk.org/index.php?topic=153232.0for ways to improve efficiency.
quick comments:
41% DOA seems really high, something might not be configured correctly. Check out the link above for how to improve it.
The efficiency number doesn't have enough data yet to be accurate. If you looked at your console output, it'll say something like Efficiency: 85.85% (20%-110%), or something like that in the parenthesis. As long as 100% is inside of the range of the parenthesis you're probably ok (but that 40% DOA doesn't look right)
Payouts to p2pool have higher variance than PPS. If you normally get .016 / day on 50 btc, then you may get .032 BTC on day on p2pool and zero BTC the next. You have to keep track of your earnings over a longer period of time. If your efficiency is >= 100%, you will, on average, earn more than any other pool. The downside risks that will decrease your earnings include: how stable is your p2pool and bitcoin nodes? could extra latency creep into your connections? Do you have the bandwidth for a bitcoind and p2pool node?