Wait, why does everyone seem to know about a succubus mate? I always read the kr mainpage and the future content forum but haven't seen anything about this at all.
If that's not your character, why are you using it to make an argument? In any case, that PLAYER you used as "proof" was playing Miri wrong.
I don't have the stats yet, but I explained to you just how to increase DPS through that cancel technique, so you can test it out yourself if you have a Miri.
In any case, I have both Miri and Delia in Season 3, and Miri by far deals better DPS than Delia by a long shot. Delia's problem is that she's insanely slow, to the point of being crippled. You can give Delia enough speed to be GOOD, but Miri already starts with enough speed to make her GREAT.