Well, they fire as fast as Angels, and the trigger on the Matrix is sweet. Really easy to fire fast.
They are however gas hogs. If you play back, it's worth getting an Aardvark bolt, and perhaps a trinity regulator for them.
The only time I've had trouble is with black & white Zap. If you set the eye to read the white it can't see the black and if you set it to read the black it always thinks there's a ball in there.