The fact that this guy was wearing what has been described as a "ballistic" vest reminds me of something a retired police chief told me recently. I had commented to someone that the training I have received called for two shots to center of mass, stop and assess, and if the bad guy is still a threat then a third shot to the head (or what my police friend refers to as "the snot locker"). My friend jumped in and said too many bad guys are wearing personal body armor these days, so three shots isn't enough. He feels five is a minimum.
At the least, I think I need to modify my mindset to make it two+one immediately. If the likelihood is that an opponent is wearing body armor, why waste the time assessing, and giving him a chance to catch his breath after the two shots to the vest?