Jeff Cooper if still alive would advise to learn to hit the intended target with the stock 1911 mag and barrel rounds, there would be no need for a bigger mag or pistol.
There have been many reports of Officers firing 17 rounds of 9mm and neither hitting the assailant not anything ese but the sky. False security rather than marksmanship.
Are you saying that even officers need to carry extra magazines due to the added difficulty of shooting under intense stress, or that you are battle tested and were able to eliminate a target w/minimal shots from a single stack mag while bad guys were sending lead your way?
===I understand your comment was meant to be sarcastic, but you do allude to a very valid point. When the bullets start flying, you can throw everything you think you know out the window. At this point all you're left with is instinct and reaction.
This is where training, and comfort level come into play. My two cents is you need a weapon that you are comfortable with, and have practiced enough with to be able to use it without even thinking of sight picture for the first few rounds. If a pistol is not comfortable in your hands, it won't point in the right direction when the time counts. At least that's my opinion.
.........I had a hawg-9. It performed flawlessly, as stated above, but was bulky, heavy & ackward to handle.