In typical ARFCOM manner, I OWN BOTH
MPA9mm - I have an older fullsize model that I purchased because it was cheap ($200) and I already had a buttload of STEN mags. The gun works flawlessly but the hammer and/or sear plate can wear with use. However, these are cheap and available directly from MPA. It is inaccurate but only because it has the ergonomics of a clay brick and primitive sights (mine has the earlier MAC11 style sights). People complain of the SLAP trigger but I kinda like it. Once you get into the cadence of fire, you can mag dump pretty fast. Not full-auto fast but still pretty fast and stay reasonably on target. IF this were the only gun available you could make it work as a defensive weapon but probably not for CC.
Glock - Frankly, a G17 with a few 32 round G18 mags does EVERYTHING the MPA will do but better.
Summary: The MPA is a well-built gun. The best of the semi-auto MAC-
style guns. IT has a cool factor of 100% but in the end, it is still better relegated to "range toy" status, which is still a good reason to get one! A SigBrace fitted to an adapter available from MPA might change the real World usefulness.
FWIW- MPA offers OUTSTANDING Customer Service! I purchased mine used and MPA was more than happy to take time and answer all my questions about the gun and they even offered to give it a free inspection if I wanted to send it in. It wasn't giving me any problems so I declined.