I agree w/Gamer 1986 about the overall uselessness of homies in a gang fight. They can't shoot, except when a cop attacks you, for some reason! So that's a bonus. The MAIN reason I use 'em is that they almost always see the rival gang members before I do, esp. in cars! Then I can get out, despite their insults, and start shooting.
The only person you really need to worry about in a fight is Sweet. He always wades right in and gets himself killed! Try to get him stuck up on a staircase, then use the jetpack to go down and waste the gang members (or stay on a roof w/a rocket launcher...yes, it's not "sporting", but efficient!) while Sweet sits out of harm's way.