hm, the PBR guide looks straightforward.would be interesting to see, how chocofur has build his arroway texture setup.
i have made some quick test,with a trichromatic prinicipled shader build.the results looking the same,except for full back color.
here the testpattern i found in the net.
base color and metallic for metallic setup
diffuse and specular for specular setup
my first test with 0.9
