There is an interesting thread on this site about Trooper Coates who shot someone 6 times with a 357 Magnum full house rounds and then Trooper Coates was shot with a .22 pistol. The trooper was killed instantly although he was wearing bodyarmor while the guy he shot seemingly walked away.
There are also many stories about Medal of Honor winners who took multiple rifle shots and still having the ability to kill others and ultimately survive.
http://www.presidency.ucsb.edu/ws/index.php?pid=43454
I dont believe its caliber that will win the battle and shot placement is difficult when placed in a stressful position. I believe that volume of fire is the key.
If Trooper Coates had a 12-16 shot Glock would he have been able to put the man down? Im certain he would have probably shot the whole clip and I think getting hit by 10 .40s is probably more effective then 6 .357s.
Just my opinion....