Folks, I am surprised that nobody has mentioned the American Narrow Gauge Railroads by George W. Hilton.
He devoted considerable space to the question of gauge and why or why not it was a good idea.
Of course the standard gauge won out in the end. But I think the D&RGW's narrow gauge ran from 1871 to 1981. So narrow gauge must have had something going for it.
Besides it is so much fun to read the history.
As far as I know, the Boston, Revere Beach & Lynn Railroad was the only narrow gauge that went from steam to electric power. Now there is some narrow gauge trivia for you.
Ted Miles
Narrow Gauge Fan