Well until someone will test the theories. I guess we can discuss them. I agree the clear/black will be most effective heating the black plastic. But I also suspect the radiant heat coming from the black would be a more significant source of heat than clear. I agree that using the term "Solar Cover" is a little misleading, as the greatest benefit would come from restricting evaporation.

Back to the point of the OP. All of this really does not need to be subjective. If I had different samples all I would need is dishes of measured water and a digital thermometer. Then scale the results to a pool sized equivalent, or a factor to be used per gal, and everyone would a useful answer. It might even create a completely different answer.