I have a number of mixed feelings about this. First off, if the shooter is 50 yards away, my first plan would be to beat feet in the opposite direction. But what if the circumstances didn't allow for that option?
I have several different guns that I might carry. They range from big bore N-frame revolvers down to a tiny .25acp that I've been know to carry in certain social situations. Where you go, how you dress and what you're doing all play a role in deciding what to carry. This is a personal choice and I wouldn't dream of telling someone else what would be right for them.
Speaking purely for myself, I prefer a larger firearm. The gun I carry most often is a Colt Lightweight Commander in .45acp. If not that, then it most likely will be a S&W Model 13 with a 3" barrel. Why these two? Because I can hit what I aim at with them. Even those are a compromise when compared to a true full sized pistol.
To those who argue about size and weight, well I use quality holsters and belts and adjust my wardrobe accordingly and have never had any problem or discomfort concealed carrying even a large frame revolver.
I do own a couple of J-frame revolvers and small autos and I do carry them from time to time. But in all honesty, I don't shoot them near as well as the bigger guns.
If the SHTF, the heart starts pounding and the adrenaline is pumping, I want every possable advantage going for me that I can get. That means an accurate, reliable firearm that I shoot well. For me, little guns don't cut it.
Granted the 50 yard shot is a one in a million, maybe in a billion possibility. But even in a case measured in inches, it has to be a confidence builder to know that you and your firearm are capable of making that long shot if necessary.