CDA is more a skin/ coat issue linked to the dilution of the color, as well as the melatonin in the hairs themselves. Isabella is the dilute version of chocolate and blue the dilution of black. With proper care of the skin and a really good diet, you can "control" the effects of CDA. I think I still have an article saved on my desktop for a nutrition regimen for blues and issys. It was pretty much my bible when my blue Doberman was still alive. I'll look and see if I have it on my desktop, since I'm on the laptop right now.
Most breeders shy away from the dilutes because of the skin/ coat problems that they can have. There is no effective genetic tests at this time to determine if a dog has it or can carry for it. It can also mimic things like puppy staph infections (skin infection) or food allergies, but where those can be cleared up with antibiotics and food changes, CDA can't. It doesn't necessarily hurt them, but it does make them uncomfortable. If you live where it gets cold (and snows) I would suggest a really good, thick doggie coat.
I would love to have a dilute again someday, but for right now I'm holding off and keeping up to date on all the current studies on CDA.