If someone is going to claim I'm wrong, then I hope you have some kind of method for enforcing p2pool for PoW at the protocol level? And can defeat share withholding attack at the same time? I'm going to try to move forward instead with the other system I described. The current system is a complete dead end.
You are greatly exaggerating the problems of PoW.
In a blockchain type of probabilistic distributed consensus you can do the following attack:
1) erase transactions by creating a longer chain that does not include them.
All issues derive from this such as double spending or preventing any transactions at all.
The number blocks on top of a particular block give you some form of confidence on the stability of that block.
With a 51% attack you can deterministically change the blockchain (make a new chain that is longer) while attacks < 50% only have a certain probability of being successful.
PoS depends greatly on how random the minting process is (PoW has an element of randomness to it and this is crucial) or else you have a problem.
If I can split my stakes in a way that guarantees me to be chosen for block minting for x blocks in a row I can attempt attacks.
Of course I need 51% of the stakes to deterministically change the chain.
The mixed mining/staking approach by peercoin is actually a good compromise in this regards. The mining introduces randomness for choosing the next minting candidate.
I'm also unsure what you mean by adding reputation to PoS? So if someone tries to double spend you penalize them? that would be a huge problem because these coins would be worth less.
What happens when you move penalized coins to untainted ones etc?