I feel like Noct AST is in a bad place because there's no sense in using it so long as Dirunal is viable, since it offers better MP and better DPS. I don't get why we try to measure Noct up to SCH though. In the one area where the two are the same (shielding) they're both solid (with Noct Aspected Benefic being one of my favourite healer tools in the game), and when it comes to DPS no other healer measures up to SCH, but AST brings does bring unique benefits to the table in it's support and utility. I would never try and replace a SCH with another healer if I was pushing world firsts because it excels at DPS but if it were strictly to keep a party alive and DPS wasn't the concern then they could compete, and I'd measure up each healers utility to each piece of content, not to eachother.