Remove whirling wrists completely from EDs and make it part of one of the ranged feats -- rapid shot, perhaps? IMHO, even with full 30% increase at L1, throwing will be non-viable until L29, but if you want scaling, do something like 1% per BAB.

Why? It's currently in T4 Shiradi. That makes Shiradi 100% mandatory for all throwers. Zero build flexibility. Moving it down to T1 would be a little better, but as long as it's in an ED at all, that ED becomes mandatory for thrower. On the old system, it was a mandatory twist -- but twists didn't lock you into using a tree, they just made filling that destiny a priority.

Currently, Shiradi is so over-powered that throwers would use it anyway, but that won't always be the case. One of the main points touted for the new ED system was increased flexibility. Well, make it so. Move locked-in mandatory features into the base game or at least down to core-1 or tier-1.