I was thinking about the slight hill of grass that will be the background of the CM here. The grass is sort of a lime green color in the sunlight and it's mostly sunny all day. So then I went to Dave's pictures of both Best Red and Crimson Red in our ATP database, knowing his two would be under the same growing conditions, soil, light, etc so any differences would show. Those pictures told me that the darker red on the black leafed tips would show better against the lime green hillside. So I chose Crimson Red. I already am crazy about it. It makes the foliage have that blue/black look, I think.
It was the artist in me who made that decision.
If it had involved math I would probably have chosen white and been done with it.