Au contraire, a 9 mm will "drill" a wall where a .45 will stop because of the larger cross section, heavier bullet, and slower velocity (this also imparts more energy to your intended target rather than drilling the perp and going on to hit something or somebody else.) The British used this dictum of "heavy and slow" for years and it worked pretty well (I also have a .455 Webley, expensive to feed but fun. Same principle.)
The 9mm also is a bear to reload because of the tapered case.
The best thing for apartment dwellers, though, is probably a shotgun, with #1 shot not rifled slugs.
Great Post. I have believed in "heavy and slow" for decades. My early experience with handguns included a .45LC owned by my uncle and used on a wolverine at close range. As mean as that wolverine was, that Colt stopped him cold.