I dont see why some folks are so excited about .45's. A 9mm +P hits just as hard (400+ ft-lb) and some .40s&w hits harder (500+ ft-lbs). Any way you slice it, a hit from a smaller caliber is better than a miss from a bigger caliber. A 9mm (or .40S&W) gives you more chances to hit your target.
If I were in charge of picking a new service side arm it would be a modern polymer .40s&w from Ruger, S&W, Springfield or Glock. Those mfgs all make darned nice guns and with a .40cal you can have your cake and eat it too.
High capacity - check
decent barrier penetration - check
decent sized/weight bullets - check
manageable grip size - check
Speaking of Glock, they Do make their guns with external safeties if you happen to have a big enough order(I think the Portugese police just got some)...and I am sure a US military contract would qualify as a "big enough" order to get them to put on a manual safety.
Just based on what I have seen and shot I would pick the S&W M&P40 with the external safety. Its accurate, compact, comfortable and reliable. And Made in the USA.
One thing that does make me irate is how much time and money the US military spends vacillating over what they are going to replace their current bang-sticks with. They spend Millions(sometimes Hundreds of Millions) of dollars "thinking it over" and end up back where they started (think XM8 rifle).