An FBI agent friend of mine once refused the then new HK MP5SF on grounds that a "rifle or carbine should be chambered in a rifle caliber." Somehow, the armorer/armory dug him up an M16 Carbine, which he gladly accepted. I agree with his advice.
OK how about one in 40 S&W that uses the M&P mags. or the 45 ACP one that uses the M&P 45 mags. Of course I would agree that one in 10mm that uses the NEW M&P10 mags would be GREAT.