Back when I carried a "pocket pistol" -- a Mauser HSc, I opted for .32 ACP under the theory that there wasn't that much difference in stopping power between the two, considering the FMJ loads that were the only things available back then. I opted for the extra round of .32 ACP.
I recently "upgraded" (if that's the word) from my Kel-Tec P-32 to a Ruger LCP, which I carry loaded with Cor-Bon DPXs. My primary reason was Ruger reliability combined with the Crimson Trace laser available for the LCP.
While there have been vast improvements in the effectiveness of both .32 and .380 ACP rounds in recent years, IMHO the Cor-Bon DPX and the Hornady Critical Defense loads in .380 are considerably more effective than the best available .32 loads. The recoil is noticeably greater with the .380, indicating that the punch on the other end would be similarly more powerful.
As far as concealability is concerned, the Ruger LCP is only slightly larger and heavier than the Kel-Tec P-32. If you can carry and conceal a P-32, you can carry and conceal an LCP. If you can't conceal anything that large, your best bet is the NAA Mini-Revolver in .22 LR or .22 Mag.
Violence is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and valorous feeling which believes that nothing is worth violence is much worse. Those who have nothing for which they are willing to fight; nothing they care about more than their own personal safety; are miserable creatures who have no chance of being free, unless made and kept so by the exertions of those better than themselves. Gary L. Griffiths, Chief Instructor, Advanced Force Tactics, Inc. (Paraphrasing John Stuart Mill)