Clerics are the most useless class in the game right now. What little combat healing you need can be provided by potions, food, scrolls and items. As for most buffs; another attack/spell action would have benefited the party more than the buff in most fights anyway (sure, bless is nice to have but not a must at all).
This might change at higher levels but at least for the first four levels the only reason to even take Shadowheart is for RP purposes, so need to be worried about having to take her..
