I've always considered the .45 Colt ... or .45 Long Colt, if you prefer to think of it that way ... as a decent, viable cartridge.
When I first entered L/E there were a handful of folks in my agency that carried older 25-5's, and even a couple of folks that carried 25-2's, for that matter.
In my personal opinion, the "limitations" of it's "effectiveness" as a defensive cartridge have been caused by the limited number of available bullet designs. That's been changing in recent years, hasn't it?
Since it's generally considered that "effectiveness" is mostly dependant on the proper placement, and then sufficent depth of penetration & expansion, of whatever caliber is being used for defensive purposes ... (the often hotly debated issues notwithstanding) ... as long as the .45 Colt can deliver similar performance, with modern expanding bullet designs, I don't see why it couldn't fulfill MY perceived defensive handgun caliber needs.
Of course, then you DO need to consider the platform to be used, and its advantages/disadvantages for each individual shooter.
I still have a Ruger Blackhawk 4 5/8" Convertible chambered in both .45 Colt & .45 ACP, and while the SA design makes it "unapproved" for an off weapon, as long as I'm still actively employed, I still find it a very pleasant and enjoyable revolver for occasional range practice.
If I came across a nicely done 3-4" barreled, 6-shot DA revolver chambered in .45 Colt ... I just might decide to add it to my off duty revolvers before I retire. I always sort of regretted not also getting the .45 Colt version of the 5 1/2" Redhawk, when I got the .44 Magnum version ...
The Redhawk is a large and heavy revolver, but it's always proven to be very controllable for me ...
This current M25 is nice, but I'd prefer stainless for "finish durability" (and my innate laziness), and I'd like to have the replaceable front sight posts, although I suppose I could simply switch it out for a brass bead post (which is what I installed on the 629 Classic I sometimes use for off duty use).