blockmaxsize=1000000
I don't get it - if p2pool can only handle blockmaxsize of 750000, how can setting it to 1000000 in bitcoin.conf be beneficial? Wont that cause problems?
For me it looks like p2pool has problems with reaching the 1MB limit, but not with being close to it.
My impression after running v0.12 for about 2 days now: it has much better latency and much less memory consumption than v0.11.
So I'd recommend v0.12 (classic or core, up to your taste) to every p2pool node out there. I use
blockmaxsize=930000
in the bitcoin.conf on my node and don't have any problems with orphan rate or tx errors.