The Kriss Vectors are super sweet. I've had a chance to do a few mag dumps on one with full auto and it was controllable in 3-5 round bursts and just holding down the trigger. Certainly better than the UMP .45 and MP10 where in full auto. 50 yards on semi I was easily able to get consistent 1-1.5 inch groups.
They are a very accurate weapon and several SWAT and Federal Agencies are using them.
A fast/accurate/low recoiling submachine gun chambered in the man stopper .45 acp cartridge is the cats meow... I'd love to get one but not until we get a SBR law in this state. A 16 inch barrel SMG style gun is just stupid looking IMO and if I where going to go that route then I'd just get a AR upper in .45 like Dogfish said.