There's a thread that is a few years old where several folks operated on their A2 stocks and turned them into collapsable stocks by adding rods inside.
https://www.mdshooters.com/showthread.php?t=180811&page=7
https://www.mdshooters.com/showthread.php?t=189852
The only thing I can think of is that it could be less likely to snag on something and might kick up less dirt when firing prone. But for most of us, is that it is just another option that we might like the look of more than the 3-prong. Maybe someone else has more insight.
I'm fairly certain that most if, not all are legal to buy as a pistol. I saw that the MKE(Zenith) was on the handgun roster, so I scooped one of those up a few years ago.
I carry a Benchmade Mini Auto Presidio II. I like the Benchmade auto axis lock mechanism.
Unfortunately I just learned that it is discontinued and out of stock where I bought it. Maybe it's getting a model refresh or something then re-released.
Here's the full size model...
The wife and I would go to Cacique (pre-covid) fairly regular. It's about a 15 minute walk for us.
If you want some really awesome cocktails, Hootch and Banter is the place!
I impulse bought a Para Ordnance Para-Carry when I lived in Vegas 15+ years ago. Was going to carry it b/c .45 ACP. It is was small, pretty, and pricey. It was the last time I bought a pistol without trying it out first. It was fine with ball ammo but jam-o-matic with any HP ammo I tried to feed...
Those 229's had the half height cocking serrations on the slide. They are legacy models now, when you can find them. They used the same mags as the original P228's.
https://www.topgunsupply.com/sig-sauer-p229r-.40-da-sa-e2-legacy-iop.html