Not trying to stir any controversy, especially about something where I don't know much but I like talking about sex-links. Here's a thought:
If you have super Production Reds and used them as the roos and fine-quality Barred Rocks, say, shouldn't the offspring be every bit as good as the parents and likely, better?
Now, I know that BR's have not been kept as a commercial laying breed for the last half century or longer. A Cherry Egger, or whatever, should be able to hold its own with a Red sex-link, on the other hand.
Of course, this could be like asking A. Einstein if him having children with Marilyn Monroe could result in a "super race" of humans because of his brain power and her good looks. He said something like, "But, what if they have my looks and her brains?"
Steve
Edit: Ah, Miss_thenorth, you and I were typing at the same time . . .