I used to really follow the ballistic data, for the various loads, in the several barrel lengths, looking for results obtained by specific gun writers, who seemed to have no agenda. I became satisfied that 4” of barrel still provided a realistically thorough burn, to enable ~1400 fps with the better 125-grain duty loads. This seemed particularly true with the Ruger GP100, perhaps due to something about the bore, and perhaps due to consistent barrel-cylinder gaps. Separate from that data, I came to agree with those who asserted that 3” and even 2.5” barrels did not lose too much velocity, with .357 Mag ammo, to remain effective, in real-world street incidents.
I used a Federal 125-grain JHC, in a real-life defensive incident, using a 4” GP100, in 1993, which did nothing to shake my confidence. In hindsight, I should have “grandfathered” my 4” Ruger GP100, and 4” S&W K-Frames, as duty handguns, in 1997, rather than going along with the autoloader flow. I worked for a PD that required us to own our duty firearms, except for the shotguns loaded loaded with less-lethal, and, some special-unit weapons. After 1997, I could not turn back the clock, and return to revolvers, unless I maintained their “grandfathered” status, but, well, I had started another “1911 phase,” and had decided to try full-1911-immersion, for all handguns larger than a J-snub back-up. (After three years of concentrating upon 1911 pistols, I managed to reach the point at which I could shoot a 1911 very nearly as well as a GP100 or K/L-Frame, on a good day, with all the planets lined-up just right. Then, I pulled my GP100 from the safe, and fired a fast-paced qual, and, in spite of three years not training with the GP100, or any other mid-/large-frame revolvers, fired an aggregate group that made me wonder why I had ever set aside my duty revolvers. Sigh.)
Notably, I found that medium-large-frame revolvers seem to carry comfortably with plenty of barrel mass hanging well below the belt line. I tended to like carrying 4” revolvers, concealed, if that meant an outside-the-belt holster, at 0300-0330, or 0830-0900. I have learned to appreciate shorter-barreled .357 revolvers, when carrying forward of the hips, to allow more clearance for my legs, when sitting and squatting. Wearing a revolver forward of the hips used to be a second-gun thing, but I am experimenting with some amount of forward migration of my “primary” carry position. On the rare occasions that I wear a horizontal shoulder rig, in this hot, humid SE Texas climate, I also find a short barrel to be desirable, for concealment.
Of course, pocket and ankle carry work best with the snub-length barrels. Neither method has been common for my primary weapon, but I have used both for for second and third guns, up to and including the SP101 in size. Keep in mind that an ankle gun can be quite accessible, if one has fallen, or has been knocked down. With no weight on it, a leg can be more-readily moved toward the waiting/reaching hand.
Other than adding a bit more desirable amount of heft at the muzzle, to damp recoil, and just a bit more sight radius, I see little difference between the various 2” to 3” barrel lengths, when handling my 2” K-Frames, 2.25” to 3” SP101 five-guns, 2.75” Speed Six, and 3” GP100. Of course, only my SP101 revolvers allow an apples-to-apples comparison, due to the identical frames. Should I ever manage to obtain one of those rare true 3” Speed Sixes, I wonder if I would be able to discern any practical difference, as I readily can with 2.25” and 3” SP101 revolvers. Balance and heft are meaningful, so I do not doubt that some shooters do feel a difference.