As far as standardizing with NATO, screw it. These are American, not French, troops we're talking about.
The money saved on life insurance payouts should more than compensate for any increased cost to procure a good sidearm.
Stay well - stay safe - stay armed - yorktown
Just about all the elite troops in NATO, except for the Fr*nch, who don't have any elite, have access to some form of .45ACP handgun or another. They know what works best.
Most handguns issued in the military are either a badge of rank, or something that is only used as a last-ditch defensive weapon. Most 9mms will never be fired in combat. Rangers, SEALS, SF, etc. go looking for trouble, and know the .45 gives them the best chance of coming back.
Not every .45 is right for everyone, but there are so many fine handguns in .45 out there that at least one has got to be right. For me, the Glock in .45 is more comfortable and shoots better than a M1911 type. The slicked-up Kimbers, etc, are works of art, and I might buy one for target shooting. For serious work, the Glock is all I need. Your mileage may vary.
While we're talking close-up killing, what's the status on shotguns? .45 is fine, but nothing beats #4 buckshot from a 12GA. I'd rather have one guy with a Mossberg back me up than two with even the elegant MP5.
Issue the Berettas to female MPs, and give everyone else a modern .45.