I actually think anywhere from 2-5 boxing has great returns. I 2 boxed for a year before finding this site and had a blast. The only thing I did 'wrong' was that I boxed a prot warrior and holy priest because I was (am) an instance whore and always wanted to be ready to jump into one. I'd just recommend anyone < 4 boxing roll/spec for DPS and ranged makes this a lot easier. With multiple ranged dps you can absolutely mow through quests and jump into any 5 mans easily. But like someone else pointed out, make sure at least one of yours can heal.