I have absolutely ZERO concerns about any of my guns (other than .22lr) being more than adequate for protection. It comes down to placement, ammo type and lest we forget quantity. I can put 3 (although I confident one would work well) 9mm Golden Sabers on the same target and in the same time it takes me to re-align my sights after one round of .45 TAP from a 1911. I use GDHP for short barrels in my j-frame and Critical Defense or DPX in my LCP. Lastly, my .357 Vaquero is full of XTP just in case the survive all the rest.
I think we get carried away with things sometimes. Let's remember that we are shooting bullets from a gun and not paperclips from a rubber band. Honestly, as long as you have good HP ammo and a reliable gun, anything .380 or better should be more than sufficient for protection.
Sic Semper Tyrannis