Steel vs wood rolling stock

When did the change between steel freight cars and passenger cars become complete in a mainstream sense?

I know it was gradual and took place over time and during the USRA's reign you see the return of some composite cars (steel and wood) in the fleets.

Other than the C&S who adopted the use of steel underframes with its last set of rolling stock that it purchased and the Oahu system, were their any other narrow gauge railroads that made use of some sort of steel framed or all steel rolling stock?

I Know the EBT, the White Pass in its container freight era and perhaps the Newfoundland fleet had steel rolling stock.

Were there any reasons other than the planned elimination of the narrow gauge system that the Rio Grande never had any significant number of steel or steel underframed rolling stock?

On a different note, what challenges would steel rolling stock present that differ from wood or composite steel/wood rolling stock?

Thanks!