I wouldn't mind them increasing the proc chance to 10%, personally

The proc is too small, the AoE is too small, the heal is too small. It's useless in PvP because you're constantly on the move. In 12-person trials it might be useful if everyone is stacked tightly.

I would rather spend the magicka and cast rapid regen or even *gasp* healing ritual. Sacrificing 2 armor slots for a maybe that might prevent a battle rez or two seems rather useless to me. FYI, my main is a v14 healer who has completed all PvE content except SO (because there's no incentive to do so, post 1.6).

The standard loadout at the moment relies on the healer (3 pieces jewelery, 2 pieces armor) and seducer (player-craftable armor). If you'd like to take a tour of the item sets currently in game, I refer you to Fextralife's Wiki. The most important thing is to realize what you're aiming for.
Do you want big heals that require good timing but allow for lots of Resto Staff heavy attacks? Go for spell power.
Do you want spammable cheap heals that require alot of attention, but you'll never run out of magicka? Go for magicka regeneration.

Mix & match. Ask for advice. Take that advice with a grain of salt. Experiment. Have fun. Blame the tank.

I'm using martial knowledge, the Thorn 3-piece set, and torug's pact to heal on my sorc. works well

Oh and two piece adroitness I think