If I may be so bold as a new poster, I would like to share a couple thoughts on this issue.
If your sole concern is home defense, I have no problem with the idea of pistol calibers, but I am much more concerned with my neighborhood, city, county, state, and country.
I have chosen my arms based on availability of ammo in all situations, thus I have chosen my arms around NATO calibers. Since our military carries 9mm, .223 or 5.56 if you prefer, and .308, I have both semi-automatic rifles in .223 & 308. Scoped rifles in bolt action .223 & .308. and handguns in 9mm. I almost forgot my tactical shotgun in 12 ga.
As we are all limited to what we can reasonably carry, it makes a battlefield reload possible regardless of the enemies involved.