So a hard p2pool fork?
Sorry I guess I'm just too used to BTC devs running screaming every time a hard fork is mentioned ... so I didn't think that's what you were referring to.
Most of the p2pool upgrades that I've seen are hard forks:
P2Pool release 9.0 tag: 9.0 hash: 2cb4d8381e179f71ea2075cdce948ea83cf0dc55
HARDFORK: Upgrade is required! Hardfork will happen after 95% of the pool's hash rate has upgraded. Everybody having not upgraded will be split off into a tiny P2Pool.
M