I should clarify--when I say "healing," I'm not talking about simply healing hit point damage. Sure, a spontaneous divine caster will be fine at that. I'm talking about ability score damage, negative effects such as fear, blindness/deafness, curses, negative energy drain, missing limbs, insanity, fatigue/exhaustion, disease, poison, and raising people from the dead. Unless a spontaneous divine caster devotes his entire spell list to dealing with these negative effects (unlikely), the party using the UA variant darkbard wants to use is going to be losing a significant amount of their healing resources. This has a huge impact because it severely limits the party's ability to deal with such conditions. Many classes can heal hit point damage--that's not the issue. The issue is the loss of the ability to deal with the whole spectrum of negative effects that clerics (and to a lesser extent, druids) are needed to deal with. This is what places the favored soul firmly in the camp of "secondary healer."