Hi,
There is a mis-conception that narrow gauge has to be low quality construction and the standard gauge had to be high quality construction.
The DSP&P had high quality engineering - look at all the long term rock ledges that the D&RG did not use. Sometimes quick and cheap allows you to get the upper hand and allows you to win.
Does SG mean best? - look at the 50' and 100' radius curves in Baltimore, New York, and/or any other dockside operated by the B&O, NYC, PRR ...
The "better" microprocessor in about 1982 was the MC 68000 (64 bits) but who won the market - IBM ISA or Apple?
Just my point of view.
Doug vV