This is not an argument ... no one thinks with the new .38 Plus P rounds, that a .22 mag is a better man-stopper on a same hit location comparison, no one. If that is the question the bigger bore with new parameters is a better 'stopper' hands down if bullets truly worked all the time ... they don't...
So I say stick to the bigger centerfire for serious work.
Exception: The folks with problems handling recoil, which the .38 has none, but everyone is different, the .22 mag is a good choice when no carry is the last choice. I would not want to be shot by one, that is for sure! The .22 long rifle has killed elephants before!
Considering the fact the some have lived long enough to kill the victim after being hit with slugs, double O buck, and more, these druggies so high that they do not feel pain can walk through .45 slugs as well ... this does not mean shoot lesser rounds for grins, no, it means shoot bigger for higher percentage stops, but shoot bigger only if you can handle it. In any case do not expect the movie version of bad guys going right down, or the couch potato version of this will kill better or that; that person may not have not even killed a stink bug, and has no standing in his advice!
Whatever you choose to carry, and you will carry it, I will have your back, it is your life. In my case, I like the slighter bigger at least, and for most cases most of my carry guns start with .45!!!