The RGB 127 is nothing more that a middle of a RED color..with intensity of 50% something that is between the dark and light.. thanks to this color used as a base for your diffuse color the light bring it in balance.. and your models are not over exposed in unatural way.. 127 127 127 is my favorite color too, it bring my eyes to balance too and relax them, this is magical grey scale.. you know that special red don't affect the photo film ? b/c it is the middle of the colors, light and darknes, even used as a filter for the lamps by the army , this way the lights are harder to detect.. I use this for all my model surfaces.. I even have partial painted walls in this color in my living room but in the color scale not grey... I saw that somebody have a quick light in his brains and changed the surfaces in poser to 204 204 204 and the rest follow it too but that was funny mistake ..and so wrong

Alex, the all elements in your render are balanced and looking wonderful, I do not like the surface of the male model, the shadows are to strong on him.. this is a day where the shadows are very soft as you did with the other objects... he should have not to intensife color and more faded out without to much specular , and blend into it as the rest of the objects do.. this is not simple to do.. but well you set the scene correct and with precision ..

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