re: Looking at buying an AR pistol and don’t know if the extra cost is worth it.

The thing that makes 5.56/.223 appealing is that at high speeds, it's been a minute but around 2300-2500fps, the small projectile fragments/"explodes" on impact. This increases the wound cavity and also makes the 5.56 a great home defense round because it penetrates fewer walls due to the fragmenting and energy dissipation from fragmenting on impact of the first wall compared to shotguns, handguns and other rifles. In order to achieve this velocity it needs to be fired from a ~10.5" or longer barrel. Some companies do 10.3". If you are not getting this fragmenting you are making a .224 hole in whatever you shoot which is essentially the same as shooting a .22LR. .300blk fills ones specific niche where it thrives and that is less sound when suppressed out of a short barrel using sub sonic ammo and mimics a .357 mag ballistically (including wall penetration). Outside of that very specific niche, there is always a better round than .300blk you can shoot from an AR. For home defense and range use I'd rec a 10.5" barrel in 5.56 for max maneuverability while still capturing the upside of it's ballistic qualities. Adding a suppressor is also ideal, but will not increase velocity noticably because a silencer "bleeds" the pressure while actual increased barrel length harness the pressure to produce more velocity up to 24".

ETA: I'd rec 55gr VMAX for home defense in a 10.5" AR. This will provide enough pressure to push the projectile to the desired velocity out of that barrel length. Also you will need an H1 , preferably H2, buffer weight for this gun to cycle reliably. A lot of cheap companies will probably ship the "pistol" with a regular 3oz buffer weight.

EETA: unless you have an adjustable gas block or BCG to tune the gas. Then you could run as light of a BCG, buffer weight, buffer spring as your gas tuning would allow. Bear in mind the addition of a silencer will add back pressure which will increase the amount of gas mitigation you need to use whether that be using a gas block/BCG to exhaust more excess gas or using a heavier buffer weight/spring/BCG to absorb the extra energy. But I can tell you from experience a full auto (aka pushing the gun to it's max) 10.5" suppressed AR will run flawless with an H2/H3 buffer weight or reduced gas from an adjustable gas block. If you have cycling issues from a short barreled AR, while it mimics under gassing, it is likely from over gassing and increased weight or gas bleeding will fix it.

You really ought to shoot one of these before buying. They are insanely loud, shoot fire like a flamethrower, blast your face with gas, and much more recoil than you're used to from a normal AR.

If you decide to get one, also get a very rugged suppressor, adjustable gas block, and a PRI gas buster charging handle.

Probably going to have to change out the buffer spring too in order to get everything cycling properly without destroying your bolt carrier group.

Overall, I'd stay the hell away from that 5.5 inch barrel. Get yourself a 10.5 inch barrel in 300 blackout with a folding stock if you want small.

That is not going to be fun to shoot AT ALL