The vast majority of the time, I carry a 3" Smith M-65 as an off duty gun and one speedloader. It works, its reliable, its easy to carry and highly rust resistant. I too see the greatest chance of a off duty encounter being a knock down drag out fight that turns into a gun fight, close range, up to and including grappling range. You keeping a knife off of you with your weak hand, on your back fighting someone off of you. Fighting a carjacker through the front window of your car. Horrible grip, one handed and upside down, the reliability of the revolver seems more important to me than capacity or even sights. MAYBE I need to take a shot at someone across the distance of a parked car or two, either way, the gun is capable of the accuracy needed.
Now, If I am going to an inner city mall or wandering around the big city, I may carry an auto with an extra mag. Theres no denying the advantage of better sight radius, better sights, higher capacity particularly if I am having to go into offensive mode, hunting the shooter in a mall or finding myself in the middle of a gang fight...
Both have advantages, given any particular set of circumstances. If it came down to only choosing one, I think I could carry a good revovler for the rest of my life and feel pretty good about things.