veqtrus, I accidentally ran this on Mainnet. I failed at comprehension and read that post completely wrong.. However; it seems to be running great, finding shares and accepting connections.
Is there any risk in continuing to run this PR on Mainnet?
Also, I was going to suggest but then noticed you already included PR #314 into #327.

If you manage to activate it on mainnet and there is some bug things might get messy. Also it doesn't help testing much since segwit isn't activated on mainnet.
Edit: Your problem is likely that you haven't connected to my testnet p2pool node so you are working on very low difficulty shares.