I used to be a "caliber war" kind of guy... but that was back before internet forums. I was a Jeff Cooper disciple and I only even purchased my first ever 9mm handgun because it was mere weeks to the falling hammer of the Crime Bill and hi-cap magazine bans. Back in 1994, I had no hopes or dreams of ever carrying a handgun concealed because I wasn't in LE or driving a Brinks truck and back then where I lived (and earlier, where I grew up) a "regular guy" never had a chance at a carry license.
But I could HATE on 9mm as well as anyone!
When concealed carry did become possible, I clung tightly to my roots, or at least HALFWAY to my roots and I chose a caliber that I had always dreamed of carrying. And in October 2008, I began carrying a Glock 29/10mm much like the one pictured above. And unlike
so many enthusiasts (and other folks around these forums) I never saw any need or desire to drift from my one carry gun. I still carry the same handgun today, but admitting *GULP* now that it's days as my EDC are numbered and I just this week purchased it's successor, and that pistol is a 9mm handgun.
Totally agree with the above post that I own .45's simply because I love the gun and it happened to be chambered in .45. I own a truckload of 9mm for the same exact reason. I don't own many .40cal pistols -- most likely due to my 10mm roots, and "most" hardcore, long time, genuine old school 10mm guys kind of
LOATHE the .40cal.
But I can tell you that when I am doing the kind of shooting I do most (steel plates at 10-15 yards) I have no doubt whatsoever that the .40cal pounds the plates harder and drops them with more authority than the 9mm does. On some plates where a 9mm in the wrong spot won't throw a plate every time, the .40cal does. That does not translate to a "BETTER" defensive round, but I can absolutely see and feel the difference when I shoot it.
I can't speak for others, but one (of many...) things that pops up often on gun forums that I personally find completely ludicrous is this idea that someone must "break ties" with a whole caliber or chambering. Like, somehow, if they own a handful of 9's and a pile of .45's but they have -ONE- .40cal pistol sitting in a rack in the safe, the .40 is going to go rogue and begin chewing the grips off the other guns, tearing in to the wall of the safe, creating a .40-caliber fungus that will slowly destroy the other guns from the inside out and create this horrendous tragedy uncovered by the light of day until the safe gets opened to see the carnage.
What the HECK is that nonsense?!
Put the pistol in the safe on a low rack that you don't pull from as often. Let it rest, let it sit, maybe pull it back out in a year and see if the mere sight of it angers you and THEN get rid of it if it does. It doesn't eat, it doesn't start fights, it doesn't suck all the prime oxygen away from the other needy guns in there and you don't have to buy or make ammo for it either.