I have a very good friend in the gun industry. He makes gun parts alot of the Special Ops guys are using, and, he hangs out with them to get feedback.
A few interesting things we have talked about. In the current campaigns in the middle east, handguns are being used considerably more than in most other conflicts. Lots of door to door fighting, room clearing etc. In some ways, they are performing some "police" type functions.
The old doctrine of shooting double taps is out. Multiple rounds per center mass, like 5 rounds per target.
A 9mm recoils less, shoots faster and carries more rounds. A 9mm is perfectly acceptable and, apparently in thier way of thinking, as effective, or at least close to .40 or .45.
Specifically the Sig P226. Its a tough accurate gun with a good track record. You may find a gun that does one thing better, or worse, but, as a whole, what more do you need from a handgun?
Alot of individuals also like the Glock 19. The big selling point of the Glock is that its as fully enclosed as a handgun can be. Less places for sand and dirt to get into the gun.
I think alot of us overthink the mindset of the guys using the equipment. Many of them are not really gun guys. Its just a tool. If the P226 is reliable and accurate, thats it. They will adapt to the tools they are provided. Based on thier skill and determination, they, and the weapon they are issued, will be exceptionally formidable. But, the actual weapon is an almost trivial part of the equation.