Well since they artificially inseminate them, I don't see why they wouldn't breed true (they actually had a segment of "Dirty Jobs" or whatever it's called on this) Usually the tom's breast is too large for him to reach touchdown. And if he does get the job done, I've read of BB hens being so large, they smash the eggs while trying to brood them. If your BBs seem to have some leg issues, better to process sooner than later. I had a tom break his leg at the hip before we could get it done.
Barbara