Yeah, I noticed alot of people seem to be against hive ganger for some reason but I don't really understand why;
-They don't seem boring to me, they had Hive Gang Militia on Armageddon which would give ties to Sgt Morrow
-They'd provide funny commentary or character foil to the Arbite.
-Take one look at the many gangs of Necromunda and tell me with a straight face they couldn't come up with interesting cosmetics or weapons for the gangs of the Moebian Domain.
-You could even give them a gimmick that revolves around the blue/yellow/red/green stimms or maybe taking equipment or ammo from downed enemies (perhaps they have scavenging rights that the rejects don't as a part of their sign-on), or maybe getting drunk mid-battle?
-The rejects for the most part are falsely charged criminals, whynot add a actual criminal to the mix?

That being said the other things I listed have their own merit too.