re
If I had a choice of weapons, I would let a pistol go poke it, and take two extra AR mags instead, however I would rather take a 4.6mm weapon over any other pistol wise, 5.7mm being my second choice.
With a hand gun in a battle situation you are not going to be hitting anything past 10m's, what with all the adrenalin going and the confusion; the 4.6mm round is as controlable as you can get, and therefore easy to use and shoot follow up shots with.
Also, it may be narrow, but it is long, and if it yaws quickly it will do far more tearing and slicing than a .45.