i think a gang feature would be pretty cool, i dont think it would exclude new players too much and would get players more into the game. you would need at least 3-5 people to start a gang, and you could teamchat with them exclusively. or you could have some sort of reputation system in the game, which gets higher the more you play (carries over rounds/disconnects), and you have to be a certain rep level to start a gang. gangs wouldn't really get any benefits, but maybe you could have some sort of feature to identify gangs, like the gang leader could choose a color and the players in that gangs left shoulder or something would be changed to that color (simulate a bandana or somethin)
it wouldn't really be alienating to new users, just another feature that encourages cooperation