Fwiw f2pool representative just post in the aforementioned thread:
Quote from: Chun Wang on btc dev lsit
Hello. We recognize the problem. We will switch to FSS RBF (*) soon. Thanks.
(*) FSS RBF = first-seen-safe RBF
Yay, I'm happy! First-seen-safe RBF is fine by me
(Although I think child-pays-parent solves all the problems with "stuck transactions" in a more elegant way.)