I traded my PM9 for an MK9 and slightly regretted it only because the MK is about 10 oz. heavier and not good for pocket carry due to the extra heft. It shot noticeably softer, though. The MK is a cadillac of a gun. I wish I still had the PM9, though. I can give an opinion on the CM9 in a few days. I'm hoping my LGS calls tomorrow to tell me that my new one came in. The PM and CM are essentially the same gun. I don't see the need for an upgraded barrel in a defensive gun. IMO, you can't go wrong with any of the 3.
Don't go ninjin' nobody don't need ninjin'.