While I can certainly understand why some folks would spend time thinking about specific types of ammunition, I've never been able to get too wound up about it - provided it was above a certain minimum and below that which would be used on African plains game.
So I got my .40 because the pistol I wanted was in short supply and the only one I could find was chambered in .40. Hence I now have a .40 and rather like it though I could not have predicted it two years ago.
A happy side effect was discovering that Federal HST .40 from Ammoman cost about the same as .45ACP Federal Red Box. That was nice. I suppose it's something of an advantage to practice with one's carry ammo - something I didn't do so much in .45. 'Course now that the HST has gone from 299.00 / K delv'd to 379.00 some of that shine has worn off. It's still about what Wally's WWB .45 cost locally after sales tax.
The pistol that "forced' the .40 on me turned out to be pleasant to shoot and it and the .40 make a nice pair. So, though I'd have bet I'd never own one, it's working out rather well.
I guess there's a number of folks that, before setting out to buy a car, decide first if they'd prefer to feed it 87, 91 or 93 octane and make it a major part of their purchase decision. Then there's those of us that don't ask what kind of fuel it takes until we're signing the papers - that hurts when it's a Firehawk that whines at anything other than 93.
Though the introduction was unintentional, I'm growing rather fond of the round.