I think AO was the first game i dual-boxed, or was it DAoC? Dont remember what was first

Anyway, in AO i had a Meta plus an Engi. Powerful Duo because the meta could buff the engi so much, my engi could summon a way-above-his lv pet ... then simply let the meta healpet follow the robot and go /pet hunt or something, and the robo will clear the whole mission for you while you are afk was fun!

I would prolly go for 4 Engi + 1 Meta