Discussions and debates such as this constantly make me go
with all the hear-say, assumptions, and armchair commando commentary.
Combat handguns and the FMJ calibers they fire have differences enough that there is no "best" for all situations.
As most of us know, accuracy is first and foremost the most important thing. If the user of the X sidearm is unable to get rounds on target than it makes no difference what the gun or caliber is. Likewise, if slider can be too far one way and the caliber becomes too daft to get the job done (think .22 rimfire or .25 ACP), then it is time to start thinking more oomph.
I think the US military should keep the 9mm NATO as their caliber of choice for a sidearm and when the situation calls for it (SPECOPS, etc), issue the sidearm and caliber of choice. This whole "1 size fits all" theory is for fools. I think there are a number of 9mm sidearms that have **proved** themselves over the years that would qualify for military duty (Sig226, Beretta92FS, HKx, Gluck17/19, FNx, etc).
There are so many factors in the debate that when someone is screaming 1 or 2 points they forget the other 9 that need to be dealt with.