I don't know why you would want to. He's cool and all, but has no dialogue in conversations so you're missing out on those from your other companions and their affection gains. If they really put the effort in and gave him special dialogue for your missions (mainly class ones) + possible to gain affection with your choices rather than just through gifts, I would use him.
I'm a completionist and want the availability really, even if he rarely was ever used. Thanks guys.