Purely anecdotally, I had a client ( now deceased ) that had several, um, gunshot incidents.
A 9mm, thigh wound, in and out, did not take him out of the fight. According to him, he finished the fight in his favor. I do not know what type of bullet was involved in this shooting. He told me the only reason he even went to the hospital, several hours after the event, IIRC, was an inability to completely stop bleeding from the wound.
A second incident with a .45 ACP round from a 1911 nearly killed him. He was shot at close range, raised his forearm in a defensive manner, took the round in the forearm, shattered the bones in his forearm, the round exited the arm and then went into his chest, fragments into his lungs, as well as other places, IIRC, but no major arteries were nicked. Very much out of the fight. The round was a Federal Hydrashok (sp?).
All of my other clients that were involved in gunplay were one and done, when they got shot. None of the wounds were fatal, obviously. I don't know what rounds or guns were involved. I remember one guy (also now deceased) saying he got shot with a "Hog Leg" but that covers a lot of guns.
I think, all things considered, bigger is better, but it's just not practical for me to carry a large caliber handgun.