then you must be doing something wrong...cause even before end game, my guardian and her Kira would kill 2-3 groups of mobs before needing to stop and heal up. i never even used Doc. Kira just made things so much faster. now that i'm level 50 in BH/Columi, and Kira's in Tionese/Columi, we just steamroll through everything and barely ever need to slow down and take a breather. she just kills things so fast while my guardian is a taunting brick wall. it's ridiculous. i shudder to think what kind of wrecking ball she'll be when i finally get her in full BH.
You must have been lucky then, cause, unless i use Doc, i take MASSIVE damage, thats why it feels like to me that if you don't use a healer companion, you just can't play the game, which makes me feel that bioware outright lied about the companions 'use any of them and not feel weakened by them' i surely do, from experience, its use a healer companion or be extremely weakened.
When i was leveling up the guardian, i was passing all the quests that people had trouble with, with no trouble at all with Kira and when it got to the point of getting Doc, the difficulty just got so high, it was use Doc or just die.