I can state unequivocally that the Beretta is the superior weapon, hands down, over the MP.40. The reduced size MAB.38/42 series (42, 43, 44) is lighter, smaller, handles better, is better designed, more simple, and eliminates the most glaring design defects of the MP.40: The magazine, recoil assembly, and firing pin. The Beretta double stack, double feed 40 round magazine (like a Thompson) is the same size as the MP.40 double stack, single feed 32 rd. mag, which should not be loaded to capacity and cannot be loaded to capacity without a loading tool. The MAB lived on and was successful long after WW2 and the MP.40 and was only eclipsed by Uzi and MP.5 designs.
I did some fairly serious work on one of those for a guy a few years ago. I testfired it quite a bit. These things shoot like a rifle and are very reliable and accurate.
Strange ejecting to the LEFT though.
Pete