I didn't see a new M-9 mag in the FMF fer my last 10 years... only the shooting teams and the boys at the weapons lab had any new gear... M-9 is junk... why do you think the MEUs issue modified 1911s?...
Because they know the same thing that most police departments have learned, and SOF has known all along. A 9mm needs to be a hot round, with a very expanding bullet design, to be an effective stopper. Unfortunately, the Hague Conventions say FMJ-only. That puts the "legal" 9mm back into the pipsqueak category.
If you MUST use FMJ ammo, the .45 is the only way to fly. It gives the stopping power needed, while still conforming to international conventions. A bit of digging around will show that elite units of almost all Western countries have a .45 handgun of some design or other for troops that are serious about killing with a handgun.