First - not trying to enter a holy war - just giving my experience and opinion...
Never owned a .40... I've shot plenty of them (and .357 Sig...) but never liked them as much as the .45. First carry guns were 9mm - and after a bit more reading and discussion of wound ballistics I came to the conclusion that I wanted more. My G30 gives me 10 rounds of 45 (+ a couple of spare mags makes 30 on my person). I found the similar frame .40's (compared to my G30) to have a much "sharper" recoil - I enjoyed shooting them less, and I found second shot placement (or second shot target acquisition time) to suffer with that platform (generally - when comparing the G30 to the similar subcompact glocks in .40 or .357sig). I'm a pretty big fella - and not recoil shy - but after putting a bunch of rounds through paper trying to convince myself that a couple of extra rounds of .40 would be worth having - I just found that when I compared patterns I shot better patterns faster with the .45 - and I was not willing to give anything up in that space.
So - no need for anything smaller than the G30 - and if for some reason I do have that need, I'll take the SP101 .357 with Glassers in the house and either hot/light .38spl +P loads - or 125gr / mid-power .357 loads out in the woods.
Anyway - had to comment as I had never understood the .40's place in the market given their recoil tenancies in lighter guns and the availability of mid / high capacity compact .45s.
EDIT - oh yeah - had meant to mention - when I head out to shoot - I take a box of .45, and a ton of .22. The .45 gets used up practicing double tap patterning, and the .22 will move a can or plate, or punch paper just as well as the 9mm - and at 525 rounds for $20 - I can afford to plink a LOT more with the 22 revolver or semi than I would be able to afford with 9mm, 380, 38, or any of the less expensive "personal defense option" rounds.
SECOND EDIT - in a larger heavy carry gun I might not have the same issue with the harsher / sharper recoil - but then again if I were to look for a full sized open-carry pistol I'd look at the .10mm and other options as well.