AST needs several nerfs in my opinion.
I'm up to 63 right now, basically leveling it as a test to see if it's as OP as everyone says. I mained SCH in HW and main WHM now in SB so I've done most content with both other healers.
I have recovered from things as an AST in Noct that would have wiped the group as a SCH. I have had everyone down but the tank and I, next to no mp and mostly burned cooldowns and still recovered 4 man dungeons thanks to card utility. I have shielded people through ridiculous vuln up stacks instantly. I have mitigated tankbusters with a combo of shielding and regen to allow my tank to not pop any cooldowns and still barely have their health move.
This may seem like bragging but it is in no way a credit to my skill as a player and in every way due to the insane heal/shield potency, utility and reactive healing capabilities of AST.
If I, as a complete newbie to the class, am able to pull off some of the crazy saves I've made on AST when I haven't even gotten all my hotbars 100% set imagine what a dedicated player could do? There is basically no need for other healers except maybe for a WHM for 8 man content and even then it's only a WHM because they have the best healer DPS and Noct AST could solo heal anything with a much lower necessary skill level than any other healer.
I don't care what entitled AST mains think - this class needs to be hit and hit hard if we are ever going to have anything resembling healer balance.
People say as long as AST can heal things Balance (the card) will always make them the preferred healer. Maybe that's true. If it is though then we need to gate Balance, like any OP ability, behind some crazy cooldown/use restriction. If that has to be AST's healing potency dropping to 3.0 or lower then so be it.
This class is currently being ruined by the lack of difficulty it presents. I would love to main it at some point but it is basically like turning on an 'easy mode' or something which is not what I want out of this game.