I had an RRA 9mm CAR-A2 that was a hunk of junk. It went back to the factory twice with problems, but still never ran well.
With original Colt mags (old stock metalform-made mags, not the cheezeball new C-Products mags) and a few scarce and expensive varieties of ammunition (strictly +P name-brand stuff), I only had around one stoppage per two magazines or so. That wasn't cutting the mustard for me.
I sold it and bought a Colt (not 9mm, regular 6920) and could not be happier with the tradeoff.
Personally, I've given up on the whole pistol-caliber carbine concept, but if you must, GO WITH THE COLT.
"A human being is primarily a bag for putting food into; the other functions and faculties may be more godlike, but in point of time they come afterwards."