your likely not going to kill or stop the criminal breaking into your home either .. shotgun with bird shot is ridiculous for home defense.
be proficient with the real tools and its not an issue. learn how to place a Glock 19 9mm round 15 times rapid fire into your target to stop the threat.
bird shot in a shotgun just going to get yourself killed . um its for killing birds, not whacked out 230 pound meth out criminals breaking into your home.
that being said. a shotgun is a great weapon, have one next to my bed.. but it don't got no "bird shot" in it. bear slugs and 00 tactical buck shot.. the ax is preferred choice though for some thug breaking into my house
on a side note your point about calibers . um you should just own all of those calibers. I do and I reload them.. its not a matter of either or its both