I see a J-Snub as an occasional gun; any occasion which suits its size/weight equation. I cannot consider an Airweight or Airlite J-Snub to be “primary,” because the little things vex my aging, aching right thumb/wrist too much to train with them, and if I won’t train with a weapon, it becomes more of a liability, than an asset. My only solid steel J-Snub is a stainless steel Model 632, and I am not quite ready to step-down to .32 H&R as a primary defensive cartridge. So, a J-Snub is an occasional gun, for me.
“Occasional” covers such factors as NPE, pocket, ankle, and various, assorted niches.
The SP101 is larger enough to be a much better shooter, and its grip larger enough to be much kinder and gentler. I have no trouble considering an SP101 a “primary” handgun, as there is room on the grip for my pinkies, and good sights, so accurate, controlled shooting is practicable. My hands are long, but not wide, and my fingers are skinny, so, I can get my pinkie onto a J-Sbub, even one with boot grips, but the factory SP101 grip extends to the “heel bone” of my hand, for infinitely better stability.
An SP101 is too big for truly deep concealment in most pockets, and on the ankle, one does feel the weight, after a while. This ensures that a J-Snub does continue to have its place.
Another factor that keeps J-Snubs (and the SP101) relevant is that small autos vex my aging body parts. I find myself gravitating toward large autos, with plenty of gripping surface, and design features that minimize muzzle flip.