Well, I don't have anything against it on principal...a machine pistol with a shoulder stock chambered in a round with some decent power is nothing to sneeze at.
When you take that same gun, chamber it in an underpowdered, overpriced, and unavailable cartridge, remove the ability to attach a shoulder stock (without $$$ and paperwork), and make it semi-auto only (again, w/o $$$ and paperwork), and sell it for more than a quality handgun...not so much.
I would prefer a Nagant revolver for a novelty piece. At least you're only out $79 then.