Having owned (briefly) a single-stack .40 and as one who runs a double-stack in action pistol, IPSC, and bowling pin events, let me just observe the following:
1. IN A 1911 - and ONLY a 1911 - copy, you can "load long" and get some effective loads without compromising reliability or safety. This is NOT an option for Glocks and other tarted-up wonder-9's.
2. My 170 gr. LSWC over about 4.3 grains of Red Dot takes pins off the table very nicely.
3. As others have noted, .40 S&W brass is ubiquitous and, therefore, very inexpensive. My local PD's are a marvelous source, if I get to the range before the other scroungers beat me to all that once-fired brass.
For that matter, I had no reliability problems with SAAMI-length loads; I went to the long loads after seeing all the L10 IPSC hotshots doing it.
It is argued that a long-loaded .40 is really a 10mm. Conversely, that would make a light-loaded 10mm a .40. So, why spend extra money on brass and primers only to:
a. Get the same result, or
b. Fight the recoil and muzzle flip
of the 10mm when figting a clock?
Best of luck with whatever you select.