They're both pretty awful. Look good on paper, provide little practical benefit.
As others have said, this is another reason why it's important to examine what AST provides in context of what the other healers provide.
I would trade CO out for Assize in an instant. Or Tetragrammaton for that matter, if we want to compare capstones.
CU I would trade for a Klondike Bar...but I would settle for Asylum, which is far more useful, despite its lower potency, and far less situational.
