The problem I see is that it's a snapshot on our scalable stat and it's why there is a maximum benefits for ES when we have 20 stack GoAK, prepot, ...
But wings is an extra damage bonus and not a bonus on our stat (so don't taking in account by snapshot) so we can consider that we will have the maximum benefits for Es' damage with wings (if we only considering this cd) if wings share a full common line-up.