Alex..When you export light probe to use with poser at the export time use the display curve gamma 1,0
not the 2,2.., in case you use all textures and backgrund in gamma 2,2 then it is fine...
correct the light probes and trust your eyes, set the collors to most natural as possible, use the pre set Photoreceptor to correct the light probe in Artizen..if you use it... if HDR SHop then set the exposure down until the natural blue sky show up in balance with the rest..  and I can't wait for the result to see.. if you do right your surfaces will show right.. I don't know if the shader nodes you use will work with the HDR light I don't have it so I can't tell.. so try to put some regular object with white diffuse color so I can see what is going on lol... 

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