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.
I mined a bit on p2pool and I'm pretty sure this is not true.
The rewards on p2pool are exactly the same as any other pool. There's larger variance than some pools, but honestly I have no idea why this is such a huge concern. It's as if people are going to mine for 1 minute only, and they want their 1 minute's worth of reward and they're not prepared to wait longer than that for the variance to even out.