Hey dubcat!
Really awesome guide!
I have a question, I downloaded your material, and noticed that it doesn't have the PBR mode checked, is it because it's made with corona 1.4? Or you did that for a specific purpose?
Also, I am creating my materials in substance designer, but I can't find any way to customize the bitmap exporter. There are some options when using the Basecolor/Metallic/Roughness converter (standard, vray, corona), do you have any tips for this? Or do you think it would be better to just import the material in substance painter and export from there?