How secure does the pool have to be? You are paid out as generation when a block is found by the pool, so as long as your bitcoin address is secure, you won't be in a situation where your coins can be stolen. The address doesn't even need to be in the wallet of the bitcoin client that is running on your computer to mine with P2Pool. It can be an address in an offline wallet! You can check the balance via block explorer.
I'm no coder, so I have to trust coders, but reading the old P2Pool thread shows the software has been audited by several people who I consider trustworthy (it's been around for a while now). I don't need to know how it works just to mine, although I do have a general idea. Besides, you were content to mine with a traditional pool where you have to trust the operator. Did you read the code for poolserverj (or whatever the pool was using)? How do you know the operator didn't modify it in some way? Wouldn't it be better to need to place less trust in others?
Valid points, indeed. I always mine PPS to have some means to check the shares submitted against accepted ones. But honestly, after switching to a pool I usually checked for only the first days to get some confidence. I am credulous (spell: naive) enough to trust the operators for one reason: with the fees they are making, in the long run it does not pay off to cheat, since credibility is their most important stake (and reliability of course).
After reading a little bit more about P2Pool, I understand that the maximum loss one can take are rewards mined since the last found block (which as of today is at ~26h). That is far less risky then what I lost to BTCServ.
Yes, it's still being improved, and there was a share chain split. It was patched and fixed. I've been mining for close to a year now, and since switching to P2Pool I am very happy with the stability. The only time I've needed to stop mining was to restart the software to update to the newest version. About one minute downtime total in the past month. That's stable enough for me considering the other advantages of P2Pool.
I'm interested and confident enough in the idea to jump in. I'll soon put some GH into P2Pool, as soon as my BitForces arrive (no kidding).