I've used him on my Sniper since it was level 1 (now 45) and I haven't had any trouble at all. Our dps output is amazing we just run through mobs. Snipers have a threat drop skill so if the enemies happen to all be on you, you can just pop that and HK actually generates decent threat because of his dps. It helps if you send him in to attack first against the bosses. And you can let him use all your old gear because he is able to use cunning.