The reason P2Pool never took off is because it's performance and rewards are sub-optimal and pay out less than other pools (only slightly but it's been enough to keep P2Pool from having wide adoption. )
So far as I can tell none of the major pools have committed either way and no mined XT blocks have been found.
this is true. but i'd argue, this is exactly what we want to see and represents creative destruction in process.
disadvantaged p2pools are seeing an opportunity to level the playing field by attracting pro-XT hashers over to their pools to gain marketshare. if we are correctly surmising the "economic majority" favoring XT, then large traditional pools need to be concerned with this migration if it occurs. they stand to lose hashers. of course, the flipside is true as well, by declaring one's use of XT software, they too could lose pro-Core hashers. i still think XT is on the right side of this ultimately though.
one other thing. if hashers move to p2pool, what we'll get is increasing decentralization of mining, which would be a side effect of this split in ideology. and not just by hashers moving away from larger pools but by adopting the p2pool concept in general.
that is a good thing.