I just think it's better to shoot the most powerful cartridge I can handle given the situation. But subcalibers have their uses, no doubt. If I were trying to get out of Dodge with my wife and dog and essential stuff, I'd want something light and handy with large capacity mags, which the AR15 certainly is. Considering that I wouldn't want to lug an ammo can around anyway, it would seem better to have more cartridges vs. more power.

Frankly, I'd recommend getting a little bit of everything when it comes to guns. That way you can be choosy when deciding which tool is right for the job...God forbid.