I'm pretty sure the OP meant several of the 9mm "pistols" with arm braces, and there are a lot of them now. I don't see the arm brace going anywhere as it was designed for handicapped shooters; banning them could be seen as discrimination (we'll see). Anyways, the cat is out of the bag and the industry is taking full advantage...and I feel obligated to support them
I started with some PCCs, Kel-Tech SUB2K, a couple lever carbines, UZI carbine (that I plan to SBR for historical purposes
), and an older AR 9mm that takes sten magazines (which is a heavy brute). Along came the arm-brace pistols, and I've expanded my investment. While I've always seen them as capable defensive guns within their limitations, these smaller PCC "pistols" have created a very perfect niche. CZ, Sig MPX-K, B&T GHM9, CMMG Banshee...all 9mm, all very reliable, all very accurate within 100 meters, very handy as home defense options, and excellent suppressor hosts.
Outside of concealability (as a "pistol"), they are far superior to a handgun for self-defense. A sling makes them handier, a better platform for optics, a much more stable platform for more accurate and faster follow-up shots...especially well beyond typical pistol distances...so many more advantages than a regular pistol by the bedside, there is simply no comparison. However, they are niche guns. They don't replace a pistol for concealed carry or as a backup sidearm, and they don't replace a rifle-caliber carbine (or pistol?) for superior ballistics, better penetration, effective range, and terminal performance. Of course I have a few of these pseudo-SBR "pistols" as well
For those that actually train, swap out your AR15 carbine for a CZ Scorpion, or MPX, etc., for any courses that are setup inside 100 meters. They are amazingly intuitive, very fast, often more compact and lighter, and just as accurate. Most critics focus on the ballistics, which I won't argue when compared to rifle-calibers; however, those same critics often carry a 9mm CCW. Again, outside of concealability, these 9mm braced-pistols are far superior for home-defense or any situations inside the average combat engagement distance of 100 meters.
Of course there are some detractors. Most are pretty expensive (although some are coming in at very reasonable price points), we are at the whims of the BATFE with the use of arm braces and the various, often-changing definitions, and you're still shooting a handgun round, albeit more on board than most handguns. Oh, and their like Doritos, you can rarely just stop at one
ROCK6