Carried a USP-F .40 as a duty sidearm. I like the cartridge, but it has more felt recoil then the lower velocity .45 or the lighter grain 9mm (not the 147 +P+ stuff). Its a great round, developed out of the whole 10mm idea. One of its best features found for Law Enforcement was that it had the lowest chance of penetrating level IIIa body armor when compaired to other pistol cartridges between .32ACP and .45ACP. Since this is the body armor most police agencys wear when this was discovered it became a nice selling point.
Really .45, .40, 9mm, .38, or any other pistol caliber over .25cal is subtible for self defence, some people just have a need to identify with one caliber more then others. I like to call it the my daddy sindrome, My daddy had a 1911 .45 there for it is the best gun in the world for ______. Really, the best caliber is the one you can shoot the most accurately and consitantly because shot placement wins gun fights, not capacity or bullet weight. Case in point, I carried a .40 cal as a duty weapon because it gave me the best mix of accuracy and power for a full size combat handgun. I carry a 9mm for concealed because it was the weapon I can employ the best in that capacity. And I use a .357 Mag loaded with Semi-jacketed hollow lead nose .38 special in my house gun because thats the jobs they do the best of the ones I have.
As far as the manufacturers war goes, H&K and Glock are both better guns then many of the ones out there they compete with. My beef with Glock is that they are not in the class that they have slowely priced themselves into, Ive seen Glocks for as much as a SIG, they shouldnt be that expensive. And I have an understanding as to just how useless 3 of thier pistols are, one goes *Badadadadada* from a proffesional standpoint.The reason you see a lot of LE agencys using them is because they are very cheap to keep and feed as an agency, Glock can underbid anybody else if they really want to. And they typically send your guys to school for free to get their certificate. Weapons for LE and Government has a lot more to do with Politics and Financial variables then with actually aquiring the absolute better weapon.