Putting aside the obvious tactical mistakes and the debate over weaponry, the reason that Platt performed as well as he did, after taking serious hits, as compared to the FBI agents, was better training.
Despite a lot of hype about it being a Butch & Sundance type go out with a bang / suicide by cop deal, Platt and Matix's main objective was to escape, and all their actions during the firefight support this.
Platt's military training was to focus on his objective and to eliminate any threats that interfered with that objective. He did this in the way he was trained, by aggressively engaging those threats, even after he had been seriously injured.
Platt's charge, where he kill Grogan & Dove, and wounded Hanlon and McNeil occurred after after his fatal wounding, and after the wound that disabled his right hand. Still, he improvised a way to continue firing his weapon and achieved his objective, which was eliminating the return fire that was preventing his escape. Matix, though receiving a devastating head wound and a potentially fatal neck/chest wound still had enough situational awareness to realize that Platt had taken Grogans vehicle and join him there.
On the other side though, we have Grogan, Dove, & Hanlon who failed to take any type of action to stop Platt after he gained a tactical advantage. What happed to Grogan, as I mentioned earlier, is the big mystery to me, but we also have Hanlon, who was wounded in the hand and had an empty weapon, but otherwise mobile, and Dove, who was unwounded but had a disabled firearm, both of whom basically let Platt walk up and shoot them execution style.
This is where the FBI had a major training failure. The agents all performed pretty well in the firefight as far as their training went, but when the situation escalated outside the parameters of their training (after they had received wounds/been disarmed), with the exception of Mireles, they failed to perform at all. No attempt to escape, no attempt to physically over power the partially disabled Platt, they just passively allowed themselves to be shot. That's the training problem that the FBI needed to address after the Miami shootout.
I have no idea if they ever did or not.
I have never been in that situation but regardless of training its tuff to imagine anyone just sitting there giving up and waiting to get shot. especially FBI agents. I surely can't see myself just sitting there. maybe they thought they were done regardless of their actions and maybe just maybe the bad buy would let them be if they stopped showing hostile action. maybe they felt at that moment that was their ONLY chance at living. thats the only thing I can think of.
some ask why the body armor and heavy weapons were not used. its apparent to me that the FBI felt a great sense of urgency to take these guys out. waiting and organizing themselves could have potentially let the bad guys escape. to me the real lesson to be learned is how to organize a force thats prepared to deal with the situation in a way that doesn't let the bad guys escape but still allows a greater degree of preparedness.
I don't really see 9mm vs 40 or really worrying about specific cartridges being much of a factor. just give the agents glocks and access to short barreled M4's as far as weaponry. add in some body armor and these agents would have been fine, with the possible exception of how they chose to take the guys down and pinning the vehicle.
