You make some good points. I usually carry concealed in public, sometimes carry openly in public, and always carry openly in private.
I respect Mr. Ayoob, but I don't agree with "give him a wallet with a few bucks and maybe he'll be satisfied, maybe he won't kill you". If someone threatens me with a lethal weapon, the only logical assumption is that he is going to use it on me. I won't be listening to what he says, I won't be thinking about the value of any of my possessions, I will be thinking about surviving. I will move and shoot. That's the only point of carrying a defensive weapon, openly or concealed. If you're not going to resist, why bother taking any self-defense measures?
Also, whatever surprise value gained by the victim exposing his concealed weapon is offset by the perpetrator having the first move.