That being said, your suggestions for dealing with these different scenarios range from leaving your wife in the hands of psycopaths to complying and hope for the best.
I am not willing to do that, especially with a family member in danger.
Ever been in a fight? I'm not talking about the shoving match you had in the second grade, I'm talking about a real fight, one with serious consequences. I find the "hero" persona is very pronounced among people who have no experience with violence and think that the Kel Tec .32 in their pocket is the answer to all of life's tactical problems. It's real easy to sit behind the screen and calmly post about how you will prevail over multiple opponents who have you seriously outgunned. After all it's the internet and the good guys always win.
Real life isn't so clean. People shot with handguns, even major calibers causing fatal wounds often stay in the fight long enough to bring the fight to a draw. Firearms aren't death rays. The chances in any of your little scenarios of you starting and then stopping the fight cleanly with a handgun are pretty slim. In every example you cited there are other people who's lives you have to consider before you start shooting.
Very few bank robberies end with anyone being shot. Why in the world would you want to start a gunfight that you probably aren't equipped to stop and turn what will most likely be a normal robbery with no one hurt into a blood bath? For the glory? So the mayor and police chief will give you the key to the city and a parade? So the bank adds you to the executive bonus list at the end of the year for keeping them from losing the $2500 or so in insured money that they would have gotten from the cash drawer? So you can post on the internet what a bad ass gunfighter you are and bask in the adulation of millions of unknown gun enthusiasts?
You also said that you would not use force when you have an obvious advantage, perhaps even when few or no others would be involved.
What obvious advantage, shooting through plate glass? Being behind the bad guys? First off it's absolute folly to try to have a gunfight through the plate glass windows. There is nothing in that bank lobby that is going to be cover from rifle rounds so waiting for them to get in the door before engaging is a not the best plan either. As for being behind the bad guys, how do you know there isn't another armed person you haven't spotted watching their back, securing the outside of the building? You draw to calmly shoot them in the back of the head and the tail gunner takes you out, the shooting starts and your wife and maybe several other people die with you. Assuming that there are only two, especially since they are obviously attempting a take over robbery is foolish. In the case that started this discussion there were going to be more then two robbers. They were caught before it happened when the third chickened out or got religion or something. There would have been at least one bad guy outside, maybe more. You make no allowance for that in your straw man argument for taking action. What you see as an obvious advantage most likely isn't in a take over robbery. There is a reason that the police don't charge in shooting in those situations any more.
Do you carry and if so, under what conditions would you use?
Yes, and I would use force when and only when my observations of what was happening at the scene, my knowledge of my abilities and my experience and training told me that using force was the best or only option. See we can play the silly game all day long of you trying devise a situation where I would have to agree that yes force was called for and I could continue to come up with reasons why it might not be the best course of action. You can play these scenarios out forever. But in the end it's going to come down to what you know or think you know when it happens. To puff one's chest out and declare I'm charging in with my pistol to stop the robbery is just posturing.
Maybe it's time to put my battle rifle back in the vehicle.
I can see it now..."Um, excuse me fellas, would guys wait there, I need to run back to my vehicle and get something, I'll be right with you."
Just using a little sarcasm to point out that when the fight comes to you it'll most likely be what we used to call a come as you are war. Yes I carried an AR in my squad car, and yes it came out on every call where it seemed in advance that there might be gun play. But it definitely wasn't a reactive weapon. We carry handguns because it's inconvenient and not socially acceptable to carry a rifle everywhere. If it makes you feel better, by all means carry it in your vehicle. But I would base a lot of my planning on actually having it to use in a fight.
The M-203 grenade launcher, which I BELIEVE takes the same ammunition as an M-79, will arm in ten meters. I don't know that you'd get outside your own back blast but I'm almost positive it would arm
The FM says 14-27 METERS. That's 45 feet, 6 inches to 87 feet, 9 inches. That is a pretty big bank lobby. Having seen 40mm grenades bounce out of the trees and drop on the ground undetonated because they didn't spin enough times to arm after someone thought they could fire it under the canopy, I'm going to stand behind my assertion that it probably wouldn't arm inside a bank lobby.
There are a lot of things to take into consideration before starting a gunfight. In real life things are never going to be as clear and as cut and dried as they are on the internet.