In my short lived experience of only about 12 years of layout hunting the only deciding variable of the hunt I have truly nearly just stayed homes has been on windless (dead calm), sunny (bright) days. Other than that I have hunted both gray and slight break-up wave pattern color with great success from North to South in North America. To me it is not so much the color but breaking up the condition of the hunter in the layout. I have been in the boats on several occasions in just a polo shirt that was red because of hotter conditions or even a base layer that was black (talk about contrast). But the conditions were always in windy, cloudy days in which the wave pattern broke up the boat and caused the birds to always come in what I consider off the deck. Once they have the ability to fly higher than the condition of breaking up the hunter becomes problematic. By telling you to get down is another variable all together. I have personally hunted when you had to get down and hide your face to the point you felt like a sardine in the box and other times I could have been on one knee in the boat trying to get everything in order and birds land within 10 feet. If you notice some guys place the box in the spread others set the spread to the side. You may find out an robust method that shooting birds may end up placing yourself so far out of the spread that it was crazy to even think it would work. Color to me is a perception of "What do you feel you want". In all cases the main objective is to take as much of the birds concentration off the boat. In closing all I can tell you is to experiment. Each hunt will oppose different circumstances. Do not be afraid to adjust and by all means it is worth picking-up if the conditions are unsafe or all together leaving a rig out so you and your partners can get yourself out of harms way.
Regards,
Kristan