As the drag racers say: "The only substitute for cubic inches is more cubic inches!"

Pistols don't generally push the velocity very high, and bullet expansion is a function of velocity x construction/design. Fancy expanding bullets don't offer any guarantee that they will do what the advertising claims, aka, expand not too fast, but not too slow, or not at all. By comparison, rifle bullet construction is difficult enough, even where there is a tremendously broader velocity performance envelope to play with. A fully expanded .300 Win Mag traveling a full 50% faster does not offer the same benefit as an unexpanded .450NE when it comes to making a big deep hole in something.

A big bore pistol like a .45 ACP doesn't need to depend on engineering trickery and the vagracies of nature to provide effective terminal ballistics because it already is where it needs to be.

Controllability? Sure, a 9mm may be easier to control than a .45ACP, and it may also hold more cartridges in the magazine, but you just may need a bunch of extra shots to put down an assailant whereas a .45ACP will do the job NOW.....

I submit to you that for me, I wouldn't consider anything other than a .45 ACP combined with rigourous training. A .44 special would also work but the double action of a revolver is a factor to overcome in that case. Go big, or go home.

I qualify my opinion by fully and thankfully admitting in this case that it is based on many years of theory, for I have never shot for, nor am ever likely to be in the awful position of having to shoot to save my life. I grew up reading Jeff Cooper, and others who did have direct experience with these matters though. Hatcher also did extensive testing on the subject using things such as cadavers and live animals, and my belief is that time and pistol bullet engineering marvels have not appreciably changed the game - pistol velocity is still as slow as it ever was.