I find that to be pretty cool, because unlike the slide fire you don't have to change out to a chinchy looking stock. Now I don't like to run through ammo that quick, but I would like the option though. I don't see how that is NFA approved???? But if it really is then I'd be tempted to try it out.
"No free man shall ever be debarred the use of arms. The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government"
-- Thomas Jefferson, 1 Thomas Jefferson Papers, 334