Dogie,
no Bitmain isn't using the p2pool share chain.
Right now:
Pool rate: 3.88PH/s (7.0% DOA+orphan) Share difficulty: 16500000
Third time, you're not listening. Please, actually read what I'm posting this time.
Bitmain's hashing power is on their main NON P2POOL pool for now, there is very little on the p2pool pool as to not upset p2pool.
Yep, which means it's not a decentralised p2pool, it's the same as any other centralised pool, just like mine
https://kano.is/index.php?k=pblocksUntil more P2Pool pools based on the open sourced code come up, then the hashing power can be put on the p2pool half without breaking p2pool.
Use clear and precise English

Until more pools, based on the incompatible forked code that is only running at Bitmain, come up, then, the Bitmain pool will be a standard centralised pool like any other.
The hashing power is (almost?) all on the incompatible forked code, since pointing more than a few PHs from one source, at p2pool, would cause 'issues' already stated.
Why do you keep saying "forked code"... unless you consider BTCGuild, Ghash and all the other major pools 'forked'.