I'll start by saying that I don't monitor my DPS much. I use a Breton necromancer for healing, although I recently fixed up a warden to heal because I read on the forums that wardens were better for healing in end game, but I prefer my necro and don't do end game atm. I use my Imperial necro as my main (stamina) for questing etc but I'm working on his tanking skills as evidently Imperial passives are good for tanking.
I read that the magicka necro was better for DPS so I was going to use the armoury to set him up with DPS gear too. Breton gives a few percent less DPS than an Altmer but can't remember where I read it.