what do you think about GBT pools? they should offer the same level of decentralisation as p2pool.
or am i missing something?
They do not currently— Luke's very active protests to the contrary—. A GBT pool is _transparent_ but unless you're running a local copy of Bitcoin and a running miner software that checks the work against the local copy, or against other pools— that transparency doesn't actually accomplish much. GBT pools also perform centralized payouts still, so even once someone develops software to sanity check check the GBT it still won't prevent a GBT pool operator from stealing from miners.
GBT is a good step in the right direction, when miner software evolves to add more checks (as BFGminer has been doing) it will prevent some kinds of abuses— I think miners should _refuse_ to use anything less transparent (though note: After discussing it with Slush he's agreed to add more transparency to Stratum)... but P2Pool is still the current gold standard relative to decentralization. It also has zero fees and pays miners the increasingly important transaction fees which few centeralized pools do.
P2Pool isn't free though: You have to effectively run a setup for solo mining, e.g. a copy of bitcoin-qt or bitcoind, and there is somewhat more network bandwidth usage. It has somewhat higher payout variance for smaller miners than a pool of the same size (due to the higher share difficulty), and if you don't want to get split off into a sub-pool of unupgraded miners you need to update from time to time (it tells you when a majority of hashpower is on a new version) . OTOOH, it means you're always setup to solo mine, and the p2pool technical community tends to be very helpful.
