Why are you wanting to cross the wheatens anyway? There are good lines out there in the wheaten color already that just need some good ol fashion culling and breeding. I think it would do more harm to the color than good IMO. The black coppers have more breeders actively breeding them than the wheatens so it makes sense that they would be bit better in terms of egg color etc.... but the wheatens just need that time and dedication put into them that they deserve. If you want a black copper go with that color, but if you want a wheaten then step up to the challenges of breeding wheaten. Solid breeding programs take time, money, hatching and culling. That's what will move the wheatens along best.