The majority I have read will be cbs it is the dominant gene, and the natural form of the shrimp.
It seemed that it was breeding with a black and a red would be 3/4 black offspring.
But red to red it was much more likely for red. Can't manage to find it now but there is a specific chart for breeding which states colors. Most people separate the red and black because the rcs are more desired for selling.
Quality grade shrimp of either can cost you extra money regardless of which color.
I read alot about these issues back at the beginning of the year, but don't retain this stuff exactly.