I have the Scorpion carbine w/muzzle brake though wish I'd bought the pistol instead now that I have a 9mm can. I don't shoot it enough to justify buying a short barrel and paying for a tax stamp to SBR it as my 9mm AR technically-a-pistol fills that role. It is a fun gun to shoot though!
I got into the "pistols" based on rifle and submachinegun designs a few years ago when I bought a Sig P516. They are truly handy, and very functional. Then the "disease" took over, and I now have several different "pistols" in several calibers from 9 mm to 7.62X51 NATO (Sig P716)