From my understanding, there is absolutely no difference between whether a rubber is black or red. You can make the rubber and give it whatever properties you want, and what color you want it is a matter of preference. You can make a black rubber in the same way you make a red one and vice versa. What you concentrate on is what properties you want for your forehand and what properties you want for your back hand, and then depending on the general custom of the country that you play in, you just get the respective color for the type of rubber you want. For example, most Europeans play having their forehand being red, and their backhand being black, while the Chinese players all have their forehands with the black rubber and the red on the back.
It probably makes little difference either way, though the only thing I can think of is maybe because pros are so well trained to look at the ball and their racket at the time of impact, it might be slightly easier to get a clearer picture of that moment with the greater contrast between the white ball and the black forehand surface, where as for the backhand, since the rubber is facing away from you it doesn't matter. But this would make such a small difference I really doubt it matters.