The G42 is the smallest auto-pistol that I have found, which I can use with a proper two-handed, thumbs-forward grip. So, its accuracy potential is far better than anything smaller. Actually, the G42 fits me notably better than some pistols which are quite a bit larger than the G42. This fit equation is, of course, with my individual, unique hands, so may not apply to others.
.380 ACP cannot smash through intervening cover as well as service cartridges, but can break bones, and has adequate penetration, so fits within my level of acceptability for unarmored opponents.
Age, wear, and tear have not been kind to my right thumb, hand, wrist, arm, and shoulder. J-Snubs now torture the base joint of my right thumb, at least with any .38 Special load. Compact nines, to include the G19, are now lefty-only weapons for me. The G42 has become my “old man’s” compact handgun. Just about any handgun, with a grip frame that does not fully bridge from the web of my hand, to the deepest point of the heel of my hand, is now problematic for me. The auto-pistols I will still shoot right-handed are either full-duty/service-sized, or, G42. The G42 is a uniquely helpful wee beastie, at least for now, for my aging hand(s), subject to change. (I can get all of my skinny fingers firmly on a G19 grip, but G19’s backstrap does not quite reach the bone at the deepest point of the heel of my hand, so, a G19, unless it has a WML or a comp to damp recoil, has joined the list of handguns I will no longer shoot right-handed*.)
In short, the G42 is, at least for this moment in time, a uniquely gentle weapon, for me to shoot.
The pocket-carry factor favors the J-Snub, especially in the event of a FUT, but some of my pockets pockets are more-or-less OK, if not ideal, with the G42. The G42 cannot totally replace the J-Snub as a pocket weapon, for me, but has largely replaced the J-Snub in this role, especially when a stout blade is added to the equation.
I need a G42, enough that I bought a second one. My wife is probably going to start carrying one of mine, soon, so, I will probably buy another G42, or more, soon.
I see the G42, as a personal need, for me.
*Though left-handed, I am right-armed. I chose to carry primary at 0300, in 1983, while learning DA revolvering at a police academy. So, having to mostly shoot lefty is not a scary prospect; I have been functionally ambidextrous with most of my handguns, for quite a while. The challenge, if/when I elect to transition to left-side primary, will be remembering the change of position(s) of the weapon(s).