You can see directly from your preview that Poser 12 is more accurate representation of roughness on the Metallic material (Conductor) , for non metallic surfaces the specular need to be set to half unless you have proper values , accompanied with desired values of roughness . It is not much about the glossy this time, but actually the roughness , all true metals have the glossy value of 100% compared to non metals with the default value of 50% at max , not mixing here the glossy with roughness , in PBR glossy values are mostly hard coded for metal and non metal materials, all what changes is only roughness when using bidirectional scattering distribution function workflow For Poser12 to render a proper PBR materials it needs proper BSDF nodes and this one is very crucial in this process

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