Ahh... Finally a post I have very limited, but possibly valuable experience with. NOTE: This is a compilation of BOTH my EXPERIENCES in shooting (Both MPA-30s and PM-11s) and my opinions of the two. (though this might sound like I'm in some way an MPA-30 salesman from RPB)
The PM-11 (Regular) is what I'd call an "Okay" gun. It's big & bulky, and the trigger is mediocre (not a good carry gun, but would do the job).
The normal PM-11 is a post-ban semi-auto 9mm Mac style handgun. They're reasonably accurate out to 25 yards, beyond that I've not tried. THERE ARE SIGNIFICANT differences between the RPB MPA-30, and the PM-11.
The PM-11 uses a variation of the "Traditional" style M-ll Submachinegun magazine. It has no "Mag Release" because there is a spring powered ball inside the handgrip that pushes against the magazine while it's in the magazine well. This isn't very good, becuase it's not a strong hold on the magazine. This may have been done to keep the gun from firing reliably in full-auto, thus making converted PM-11s unreliable as the magazine will occaisionally drop or lower itself in the grip, causing a jam (FTF). This is where the MAIN problem with the PM-11 lies. If fired (though semi-automatic) rapidly, it occaisionally WILL have the magazine drop too low to feed properly. Another problem with the PM-11 is the standard sights; They are not very accurate, and can be rather difficult to "locate" with your eyes under stressful (non-range) conditions, IMHO.
This is where the MPA-30 differs (Depending upon which MPA-30 Variant you have). MPA-30s are basically PM-11s with improvements. The most NOTABLE improvement is their pistol grip. Some variations of the MPA-30 have a different grip than the PM-11 which has a paddle style release on the bottom, and is designed to use the MUCH MORE RELIABLE magazines for the STEN Submachinegun. Which also are MUCH CHEAPER as well. Why buy a $20 to $30 PM-11 magazine when you can buy a $7.00 STEN high capacity magazine at any gunshow? I have only had an MPA-30 jam (fail to feed) three times, and that was with hollow-points (forgot what brand, it was 3 years ago, with my friend's MPA-30). It fed FMJ ball style 9mm like a champ, YMMV.
Another significant MPA-30 improvement over the PM-11 is the side-mounted charging handle. This allows the addition of a sight-mount on the top of the gun (which, IIRC, is a see-thru mount sill allowing iron sights). To which you could add a nice Red-Dot, Aimpoint, or OKO sight! This makes target acquisition MUCH better than using the standard Iron sights.
Thus IMHO, the MPA-30 is a MUCH better gun than the standard PM-11. $200 seems to be the going rate for a PM-11 these days, and the MPA-30 price varies significantly based upon the modifications it includes.
Some MPA-30s have only the sten-mag conversion, and standard top charging handle, no rail, etc... They vary a lot, especially if you look on Gunbroker (last I checked).
Armored Fire used to sell MPA-30s with ALL the improvements (Sten conversion, Side Charging Handle, & Top Sight Mount) for $400 at first, then they raised the price to $450 for a new one!!! The last MPA-30 they had, they put into their gun case to be used as a rental there. Since then, I haven't seen any MPA-30s for sale in their store, just the rental.
Basically, IMHO, the MPA-30 is much better than the PM-11, but you have to decide for yourself if it's really worth the extra $$, and have to find a place that has one for sale. The PM-11 was a jammomatic (which he later sold) in my experience (limited, because after I had 5 FTF jams in a magazine I handed it back to my friend & haven't shot a PM-11 since). I fired 3 sten magazines (two FMJ, one Hollowpoint) through my friend's MPA-30 (same friend who owned the PM-11), and it had no problem handling rapid fire (but jammed 3 times on HP ammo). I'd imagine that polishing the feed surfaces or something would make it more reliable with hollow-points, but I'm not sure, and can't ask my friend (former member of my old campus Armament Group), because he graduated & moved to washington state & I never heard from him since (his campus Email address was closed too).
Take this review with a block of salt (not a grain). Because:
1.) I never fired more than 10 rds through the PM-11 and was sick of it.
2.) I never fired more than 60 rds through the MPA-30, this in no way gives me the ability to say it's "totally reliable" or some such shit.
3.) I'm no proclaimed expert in anything...
Maybe the MPA-30 I shot was a fluke (which I doubt it) in its reliability, perhaps 90% of them are MUCH less reliable; Likewise, perhaps the PM-11 I shot was a fluke (which I doubt it), and possibly 90% of them really ARE reliable... Who knows. I certainly don't.
One thing I CAN tell you is that an RPB MPA-30 IS on my list of things to buy (if I ever get the money), and a PM-11 is NOT on my list of things to buy. Sorry for the long post. Just my short experince, limited knowledge, and longwinded opinions... Maybe this is of
some use to you though. You decide, you're smarter than me.
You can buy a PM-11, and buy the different modifications from RPB arms (
www.rpbusa.com - Website under constr., a large/stupid advertisement posted until complete) but these mods will also work on FA M11 submachineguns as well, without altering the receiver in any way, IIRC. You can even buy "Kits" to upgrade pre-ban M11 Semi-auto guns too. Like I said, YMMV. Go to Armored Fire, and rent their MPA-30 to see how you like it. If you can find another buy it.
Heck, call Jeff at Armored Fire, and ask him if you could buy his MPA-30 used from their rental case... You never know, he may let you, and you'd likely get a price cut... I don't know.