Faced a triple Firespray list at a tournament earlier this year. Like KF says, it is pretty daunting facing 30 hit points throwing out nine/twelve dice a turn.
I was using an XXBB list and it came down to a severely battered Firespray against a B Wing with one hull point left. I ended up losing but I whittled down 28 hit points in an hour and also gave my opponent a break as he flew off the table slightly but I let it fly.
I have only ever ran dual Firesprays though.
The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown.