Comfort.
I am more likely to get more-accurate first hits, quickest, with a GP100, Security-/Speed-Six, or K/L-Frame, than any other handgun. That is comforting.
I can shoot a 1911 about as well as my best revolvers, generally speaking, but for the first cold shot, without time to stand there and meditate for a bit, the GP100 is likely to win. This is not about gunfighting; it is about STOPPING a gunfight.
Several felons had the opportunity to look up the barrel of my GP100, Speed Six, or K-Frame, while my duty autopistol remained holstered. This was typically a planned felony vehicle stop, when I had time to uncase the six-gun, before the strobes were activated. “Back-Up” is not always smaller.
Every shot I fire with a DA revolver makes me a better DA revolver shooter. Every shot I fire with a 1911 makes me a better 1911 shooter, but also makes me a better DA revolver shooter. Every shot I fire with a Glock makes me a better Glock shooter, but also makes me a better DA revolver shooter. I can train-up to be comfortable with a 1911 and Glock, but a GP100, or similar revolver, remains most-comforting.
Carried OWB, a revolver, with some barrel heft, is very well-balanced, and comfortable, without the need to cinch the belt too tightly.
IWB, a revolver is slim where it needs to be, for comfort. There are two places, on each side of my anatomy, where the wider cylinder has a natural place to rest, in relative comfort. I used to carry my N-Frame Model 58 .41 Magnum duty pistol, in an Eagle Industries IWB rig, comfortably. A GP100 or K-Frame is all that much easier. (I finally admitted to myself that I have K/L/GP100-sized hands.) And, yes, an N-Frame S&W Model 58 is a pistol, a revolving pistol, just like Sam Colt’s patent states.
If I have to “Mexican carry,” for the sake of quickness/expediency, well, nothing, and I mean nothing, is as stable, on my person, as a medium/large revolver, with about 4” of barrel. The barrel adds stability. Stability is comfortable, and comforting.
I am not advocating holster-less IWB carry, a.k.a. Mexican carry, but sometimes, well, such things happen. It is not a best practice. Keep it to a minimum.
To be clear, I am not anti-autoloader. I still use autoloaders, and sometimes carry an auto-loader, without any revolver within my reach, any closer than locked-up, miles away. (This does not mean “rotation. This means free choice.) My first love was the 1911. Choice is good. Comfort is good. Life is good.