FWIW, I would say stick with 9mm if thats what you like and shoot well. With modern ammunition the difference is made by the person, not necessarily the caliber. Not to mention 9mm is far cheaper so you're likely to practice more. Just a thought.

If You lived in another area the cops would all be carrying 9mm. Change to .40 if you want, but don't kid yourself it's because its' been proven to be the best calibre. All the major calibres have the same stopping power to within a few percent. Your speed and accuracy with a round that suits you, will far outweigh any 'advantage' of calibre. Besides what is the advantage of standardising? You planning on going on a wagon train or something?
qjs

<All the major calibres have the same stopping power to within a few percent.>

I am afraid the firearms industry, law enforcement and the military will disagree with this statement.

The firemarms industry are trying to sell you stuff so I'd discount their opinion. Guess what? They all say thiers is the best!
The military can only use fully jacketed ammo so their experience will be different to yours. They simply don't have an opinion on what is the best expanding round. They have no need to know.
And the cops follow Evan Marshall whose figures show 9mm, .40, .45, 357 etc all in the 90 to 95% one shot stop range.
qjs

geesh, is this a 'Going Green in 2011" thread. Cutting back on weapons systems simply because they are not used? JK.

I am actually considering ADDING a .40 to my arsenal. There is a nice H&K USP on co-sign at a shop next to my house.

Does smokeless powder create greenhouse gases?

I agree with the above post.

As long as the caliber chosen has adequate stopping power, to my way of thinking it’s more personal preference and how accurate one is with the particular gun. A gun needs to be accurate, have reliability and have controllability. For instance, if I take two otherwise identical Winchester model 70 rifles, one .270 and one 30-06 to the range, the .270 is an easier rifle for me to control and thus it’s more accurate for me. Granted if I had two grizzly’s coming at me at the sametime the stopping power of the .06 might be nice, however overall the .270 is a little easier for me to use. In closing when you get down to similar calibers I don’t think there is a definitive answer other than what works best for the individual.

Yep, as I have come to understand, the latest generation 9mm 147 gr JHP are some pretty good loads. I have been shooting some of the Win Ranger 147 gr and it seems to be good stuff, much easier for me to control than the .40SW. YMMV

Selling some firearms in odd ball calibers because you don't use them and never will is one thing; selling 9mm to make room for .40SW is another. I have standardized on a number of standards -- 9mm, .45ACP, .357 (158 gr only) and .22LR in handguns -- .22LR, 5.56 NATO/.223, .308 Win and 30-06 in rifle. Those are all standards in my book.

I actually ditched the .40 and standardized on the 9mm

If I were wealthy enough to own them all, my idea of "standardization" would be: slingshots with 3/8" steel and .44 lead, airguns in .177 and .22 pellet, firearms in .22lr, .32acp, .380acp, 9x18mak, .38spl, 9mm parabellum, .45 long colt, .45acp, .40s&w, .357mag, .22wmr, 5.45x39, 5.56x45, .243win, .30-30, 7.62x39, .270win, .45-70 gov, 7.5x55 swiss, 7.62x54r, .30-06, .410 bore, 20ga, 12ga and .44cal muzzle loader.