Regarding hashrates, yes you are correct. There is still the problem of p2pool share difficulty getting too high for 'low speed' miners, but the dev (Forrestv) is considering solutions to that, like multiple sharechains, etc.
I'm also thinking about ways to create a hybrid node. A centralized node, if you will, running on the P2Pool network. This will allow me to create services similar to the other centralized pools (whatever people especially like about GHash), while still making them indirectly mine on p2pool. There's still the risk of the hybrid pool growing too large (eg >51% of the sharechain), but that's a serious problem already...Petamine were going to trial p2pool, but it looks like they didn't, because they would immediately have had >50% of p2pool's mining power. Things like hybrid nodes would be more useful when there are large mining groups on p2pool, so smaller miners could still turn a coin.
Thanks for another really interesting post.
Alright, so that's something I didn't know: that p2pool doesn't scale that well yet assuming a big increase in hash rate. Is this solvable, in the near/mid future?