Well the reason i use one as Holy and the other ret is cause i need someone with alotta mana and bigger heals. Reason is that i pull large amounts of mobs and then consecrate them down. They usually run away and bring back more mobs and i rinse and repeat consecrate. Hence were my mana problem is coming from. I kill mobs in no time and if i had both ret i wouldnt kill them too much faster but i would die a whole lot easier. Once i get high enough that i get more powerful ret abilities i will switch both over.