Thanks for sharing your nightmare story with the rest of us. I've got mine taped too. My scenario was where I had a mock gun on me. I get sprayed full-facial (I still can't believe you had your mouth wide open you crazy galoot!). Then, a friend of mine would try to grab the gun from me. I was to keep him away, and then, upon the signal, I would draw and fire.
The tape clearly shows that I was in agony, but definitely still fighting. In fact, my "attacker", even with his martial art background, I had managed to pommel him and send him rolling down a slope. And, when given the signal, I was still able to successfully draw and double tap (though I think I pressed the trigger on the mock gun more than twice).
In short, I agree with your sentiment that pepper spray will NOT incapcitate you immediately. It will ENRAGE you first!
I view the spray as a diversionary device designed to greatly reduce the opponent's fighting capacity as you move on to plan B. But one has to be very careful of the "berserker factor". I think the ideal time to use pepper spray is when the opponent isn't using a gun. That way, you can spray and run. Besides, if the attacker has range capability, it kind of nullifies the pepper spray's range advantage as well. And the pepper spray does greatly reduce the attacker's ability to run after you. But whatever it is, it is definitely not a good idea to just stop with the pepper spray. I say it would take 30 seconds for the effect of the spray to fully settle in.
The spray does work. It may not seem like it to an outside observer, but it works immediately. But unlike what the advertisers say, you just don't get results immediately. In fact, the person being spray never gets incapcitate at all. But their ability to fighting back is gradually, though greatly reduced.