It sounds a little contradictory that you'd want to include Flames of the Firebrand because of all the X/1s and X/2s in the format butThe list looks really good. As helpful as Flames of the Firebrand seems, what do you think of moving it to the maindeck? It's a lot more relevant than it used to be in a format full of X/1s and X/2s, especially since you're playing Chandra's Phoenix where pinging the player for one to get it back is often a good line of play.
As for Ash Zealot, she's really good in the mirror, but terrible against the decks that just go bigger, and those kind of decks are becoming more popular. You could fit in a couple of extra spells maindeck and run the full set of Pyromancer, but I think your updated list is just better.
also cut Ash Zealot because a lot of decks are going bigger.