Also, the Walther P22 is far lighter and easier to conceal on your person than a big old 45, 40.
If you really think you want more firepower, move to the Ruger LCP .380. Small and lightweight, but has a bigger kick.
2400 fps? Not. 22LR out of a short barrelled pistol or revolver will only make maybe 1000-1100 at max. HV and Hyper vel 22LRs only get about 1600 fps max from a rifle.
Will they suffice for personal defense? Sure, but there are much better choices. However, having a gun, even a minimal gun is better than not havng your ultra mega stomper...