I have heard about people using that theory as well. Problem is implementing it. If you have a gun on your strong side, and a blade on your weak and he goes for your gun are you really only going to try and stop him with your one hand? That's a FIREARM he's going for. Your blade won't mean anything if he gets your smoker. If you are focused on retrieving ur folder he will have 2 hands to go after your piece and unless you are very well trained he'll probably retrieve it. As soon as the struggle begins he will move to your strong side and you will be trying to spin or stab over your shoulder to get to him and he will gain superior fire power. Yours. Now all of these can be over come with training, but it's something that needs to be practiced and with a realistic partner. I would prefer to use both hands for H2H. Firearm retention. I carry at 3:30 so my elbow will clench in and tight over my firearm with my hand still at the ready while I twist away and intercede with my left hand. First will be a very fast reaction of dropping elbow in, then lowering center of gravity, then either a knife blade (straight hand) to throat or my left thumb will be removing BG's right eyeball. These reactions must be fast. Fumbling with a knife is not the best idea in my opinion. Remember we are at justified deadly force, no time for Mr. Nice Guy. Its time for Mr. Ugly.
Brownie, SwampRat, any difference of advice or opinion or add ?
IMO, implementation of this plan can be problematic as you suggest.
1. Weapon presentation [ the firearm ] has to be faster than most will have the practiced skill for or there could be a gun grab attempt, but more importantly perhaps is what is he using to try to control you with while demanding the money? Knife? his own gun?
2. If he's threatening you with a firearm beyond your reach, drawing your firearm might bring incoming, few will win drawing against the drop
3. Distraction is a tactic that can work, but not always, again what is he threatening to use to get you to comply--gun or knife, how close, what's the disparity of force relative reach and strength between you?
4. As goldsamurai26 mentions, what's your skill level with presenting your knife/folder under stress against an unwilling participant?
When you are in it for all the marbles, it's not the best time to be trying this for the first time based on a theory or tactic that has not been honed with practice as airhead mentioned. I'd add that other skills might need to be called on in conjunction with the gun or knife as has been mentioned by others like good H2H and gun retention skills. If someone is going for my gun as I'm drawing I think goldsamurai26 makes a good point that most will need both hands working to keep the BG from getting your own gun away from you. It's not an easy skill to keep your gun from being taken if he's got his hands on it.
In this scenario, with the BG threatening with a gun, distraction can create some time as DE mentions but one needs to be able to utilize that increment of time to good effect, meaning the presentation of your own firearm has to be as fast as possible and likely coupled with some type of tactical movement off line of his own muzzle. What if the BG doesn't go for the money thrown down? Makes you bend over and pick it up yourself and now he's PO'd because he knows that little trick and suspects you are up to no good? Ouch, could be a bad day if he's not that stupid to fall for that ruse.
I rather think the gun in MY back pocket where people normally carry a wallet will be my best chance of working this scenario. He expects me to reach for the wallet in that pocket. It precludes all the above and may be the fastest way to send incoming his way unexpectedly. In that case, the BUG now becomes the primary to possibly create time and distance to draw the strong side heat and get to work.