I honestly don't see why this thing would need any more power than it currently has. It's already looks like a very solid tier 2 class.
Though it does have a limited spell list, spontaneous casting from 5 domains allows you to snare most spells that you'd want (if you plan ahead), Advanced learning gets you additional buffs that you'd need, and you have more uses per day of your divine feats (and you get bonus divine/metamagic feats).
Unless I'm missing something, a healer can battle as a persist spell self-buffer fairly well (especially as there are so many buffs in the spell list). Even if the bad BAB looks like it prevents this, simply persisting Divine Power is enough to be a brawler anyways.
In fact, a combination of bonus metamagic feats, better spells per day, and more versatile spontaneous casting (even a cleric spontaneously casting from domains has only two domains to choose from while this class can get 5 domains, 5 cleric spells of choice, and cure spells if they select spontaneous healer as a feat) may make this class a bit more powerful than the cleric in certain situations.