Revolvers that shoot the .40 S&W round have to use a moon clip since the round is designed for a semi-auto, it’s a rimless cartridge. For a pocket pistol I’d forget about stopping power and concentrate upon small. Stopping power is overrated in a pistol anyway, no pistol round really has “stopping power”. If I was planning on pocket carry I’d much rather have a 25 or 32 ACP that fit in my pocket than a 40 that I had to wrestle with and made me look like John Holmes at a wet T-shirt contest.
Well said and a very good point IO was curious about also.
Reloading is going to be a messy issue and not smooth. You would need to have several speed loaders and six moon clips to make sure you are good. And if you need more now you have to load the moon clips again before you can reload the firearm. Not worth it. .38 with +P and you are good to go no matter the situation and even if you do not have speed loaders.