The way the game is set up it seems pretty pointless to use a dps companion I only ever use Healers and I guess if I ever rolled a healer I might use a Tank. So what is the hype with the HK-51? Seems to me its just gonna be another useless companion collecting dust unless they made the game more like Kotor and you could have 2 companions.
Did you play KOTOR 1? Then you know why everybody loves him.
You can easily have him out when youre doing daily quests. He probably can tank aswell.