I'm not a big fan of the pelvic girdle shot - yes, it brings down even an opponent with body armor, but it does not incapacitate.I took an advanced pistol class years ago which used three shots like the Mozambique. But the chain starting at the pelvis. One round on pelvis, one round on center mass, one round on head. The theory was with armor or without the first shot was a more likely hit to solid flesh. It is an interesting idea, but still requires reps to master.
So, yeah, he hits the ground, but he is still a threat if he is armed. If he is wearing body armor, it's because he is expecting a gunfight, and that type of person may very well be shooting after he is on the ground.
In the 1986 Miami Dade FBI shootout, those assailants took over a dozen rounds before they gave up the fight.
I want the threat to stop, I want the assailant incapacitated - so, center mass, if it doesn't work, head shot.