For axes with < 504 delay, getting a 5-hit is very rarely worth it. It's not just Haste you need to sacrifice, but also much of other good TP stats (DA, Crit rate, Acc/Att and whatnot). For 504 delay you "only" need 46 Store TP, which would possibly make it worth it. But I'd still recommend some Phorcys gear, regardless.