I have hear that a hundred times, but I fail to see how making auto-sexing the first priority in your flock improves it. Plus If it were really that bad then you would want to cull the chicks rather than sell them so that the defect didn't persist in the breed.
I was taught to never ever ever cull based on chick down before I started working with legbars and have never warmed up to the idea of culling for down markings. What the pioneers of the Autosexing breeds who made up the members of the original Auto-sexing club of Great Brittian did is toe punch chicks at birth. They would toe punch all the cockerels with good marking with a punch on the out side web of one foot and all the pullets with good marking with a punch through the outside web of the other foot. They then would grow everyone out. Those with the good marking and those with the bad. when it came down to selecting breeder they would know which ones had good down markings as a chick and which didn't. I do the same think. Those with good markings get noted and those with poor marking get noted and I grow everyone out. I have found that that pullets with superior markings often have really poor mature plumage (over melonized). I have found that those with poor markings often have really good mature plumage (they are possibly carrying recessive color patterns that show up in the down but no the mature plumage).
I know that I can clean up poor down makings a lot easier than I can improve type so I weigh the down color with type to make the final decision on who stays and who goes. I have been doing this for 5 years and still and 100% accurate on sexing chicks. I haven't got one wrong yet. Not even the poorly marked ones.
Sweetdreaming,
Nice to see you on here again. Its been a while. No...no replacements from GFF. I am line breeding. Any time you bring new blood into the flock in creates unpredicatability in the breeding. To lessen the effects of the new blood you can select a 2-3 hens from your 15 and breed a cockerel to them. You then can take the best cockerel from that group to breed to your 15 hens next year (or in the fall). That is a safer way to do things. If the dark breasted hens have better type then it is always worth it. Color is the easiest thing to clean up. Type is more difficult to improve.
You said it so much better than I did, Thanks...