Im running Deception with Khem Val and I had no trouble at all leveling to 39. However, I just got Ashara and equipped her nicley. But seriously she suck, she seems to do less dmg than Khem with worse gear and she aint a tank. And I dont get to use exploit weakness... Switched back to Khem and back on track. Been easy leveling so far, if Khem is getting low on hp I just switch to Dark charge and taunt/aoe taunt. I also have his taunt off by default cause of this. A good idea when facing hard situations is to turn off your companions AoE/Cleave abilities and use your CCs. People say it gets easier when we get the healing companion, will see about that.
I think I died ONCE so far while questing, and I was really surprised. I usually dont even bother looking at my hp bar lol.