1. If that's what you've got, and it's all you've got, then maybe carry it, but realize "stopping the threat" is the objective, and if that's not done quickly, the threat could get really upset with you and you could find yourself in a much worse predicament.
2. Saving on ammo costs is definitely "false economy" in a life or death situation, so naaah; get a bigger gun.
3. Maybe in a situation where deep cover is required, as in the case of an undercover police officer, then I suppose this is better than a photo of your bigger gun, but not by much.
Anybody remember Ruark's book "Use Enough Gun"? Well that had to do with large, often dangerous game. My reasoning is to carry as large a revolver or pistol as I can:
a. Carry in a well concealed manner, yet have the gun readily and quickly available to me.
b. That I am totally familiar with, have practiced with and can shoot accurately and quickly enough with to bring the threat situation to a rapid cessation.
c. That is 100% reliable based upon my practice sessions, as well as shooting my more expensive "social" loads.
My go-to carry gun is almost always an Ed Brown .45 acp Commander size, or a Wilson Officer's size 1911 loaded with Federal 230gr Hydra-shoks. I find I can conceal either of these even in the middle of summer with a "one size up" untucked casual shirt. Yeah, there's a weight factor, but there's the old saying, "go big, or go home", and at the end of the day, I want to make sure I go home. If for some reason, I just can't properly conceal the .45, then I might compromise on a Glock 26 9mm, S&W J-Frame .38 or a Sig 230 in .380 auto and despite the .380's being all the rage in the past few years, I much prefer a more powerful cartridge. I always carry at least one extra magazine or 1 or 2 speed loaders, so I can stay in the fight longer,get out of Dodge, or in the event a magazine goes South, as I just don't like single-shot semi-autos.