I have a Golden Cuckoo Maran hen that is a reliable layer, and not aggressive with the other hens. She's sort of on the lower end of the pecking order. I can't make a general judgment on the Golden Cuckoos since I only have the one.
I don't know what it is with the Black Copper, but my experience with them would make me pause before getting another.
Is it the dark eggs you're after?
There are a couple of other breeds (penedesenca) that lay very dark brown eggs. OR - just be sure to only get females.
If you're just looking for a flock to lay eggs, you're welcome to a couple of dozen eggs to hatch. This year was the first year I got a successful hatch from Benzo - not his fault, last year the broody killed her chicks. They are mixes and all all very pretty so far.
Sorry.. hijacked your thread...
BACK TO SHADE PLANTS!!!!
You might be in luck!
Right now I have 1 blue EE hen (who is laying blue/green eggs) and 1 blue pullet (not laying yet) plus a couple JG chicks that are blue and a blue/grey splash. My mutt roo is part BLRW and all of his breast and belly feathers are blue. One of his chicks this spring was a beautiful blue - but got eaten by a snake before she had a chance to grow real feathers...
So.... a reasonably good chance that I'll be able to hatch several 'blue' chicks next spring.