It requires sending the entire block template (potentially up to 1 MB) to miners every 10 seconds, which is definitely impractical for remote miners. An extension to GBT that allowed only sending the merkle root would avoid this, though.
Sending only the merkle root, whether it be via getwork, Stratum, or some new GBT extension, makes the pool centralized, and kinda defeats the entire point of p2pool... Perhaps it would make sense for "remote" p2pool servers to be the first to move forward with mandatory-miner-provides-the-transactions GBT?
If the protocol (Stratum) has the option to request the transaction list - as you already know - then why are you making this statement?
Are you arguing that GBT isn't centralised because you HAVE to receive the full transaction list?
That optionally receiving it isn't good enough? Seriously?
Yeah forrestv it seems that you need to take his hidden agenda comments with a grain of salt.
His agenda is to promote GBT no matter what problems there are with it, and to use dictionary arguments to avoid transparency.