Hi, I got your update, and it seems to me that your shader is now good and usefull.
I did a test with my own pbr shader which has another approach, but the results are the same:
On the left is your shader, and on the right mine. I tested it with several variations in settings: very rough, low IOR and I didn’t discover any difference yet. So I think I will start to use your shader which is more user friendly to me. I had to turn off the specular map to get the same results as my shader. I didn’t explore it yet, but I suppose the specular map is to get the minimum reflections.