What would change for you if the price and availability of 9mm and .45 suddenly flip flopped? If you carry 9mm and don’t reload your own ammunition, would you switch to .45 for the increased availability of both practice and carry/duty use ammunition? Or would the capacity and shooting benefits (really just lower recoil/wear and tear) of the 9mm make the extra cost worth it to you?
I guess the whole question is long hand for: do ammo price and availability outweigh the shooting characteristics of the round itself?