Helios = Medica = Succor = Noct Helios (300 potency)
Benefic II = Cure II = Adlo = Noct Benefic (650/600 potency)
Diurnal Helios = Medica II (600-700 potency HoT)
Diurnal Benefic = Regen (980-1050 potency HoT)
*Note that I am using the = sign but I really mean approximately equal (can't find that squiggly = sign on my keyboard).
What seems to have been overlooked is that Succor is Scholar's version of Medica and Adlo is Scholar's version of Cure II. Nocturnal AST having access to both other healers' versions of basically the same skill isn't really that useful. Diurnal has 4 distinct healing spells and Nocturnal has two flavors of 2 distinct healing spells (not counting Benefic 1).