mouse+keyboard and the space+left/right combo make the banshee very tough to take down on h2 pc, if it is used by someone who knows how to do it. rumor has it that some people have actually given up their homes to live in a h2v banshee. also, getting the overshield with a banshee is a strategy.
you can try using a shotgun, dual magnums, dual smgs, plasma nades or a rocket launcher.
also: i am thus saying that this guy could be legit. only anticheat can tell the definitive answer.