I chatted some with Wynette, she doesn't see a problem with using a Silver with autosomal red shoulders for a one time use. It's combing two reds or several generations you'd be getting into trouble maybe.
She also confirmed my suspicions on the chick down color. The darker color chicks should not be used. Most of the females that were born darker cast still have brown cast on them at 17.5 weeks and the cockerels are lacking in crisp black and white on hackles. Wynette used the term smutty. I like that as it describes the effect well.
Here are some poor pics of the cockerel I was convincing myself to use and now definitely am for half next springs hatches. Photos don't do his back justice, it's very flat and wide. Not over amount of fluff on butt like others in flock and his white with black on hackles and coming saddle are crisp and complete. He's fantastic in all regards compared to all other cockerels hatched this year but has mahogony in wing shoulder.
That's not a split tail. Have some tail pecking issues that will be resolved in this weeks cull. Like the cockerel in back of last picture with roach back is a good example of dinner.
Great articles by Brian Reeder in Exhibition Poultry Magazine in the Fall 2013 (I think), regarding autosomnal red. Might be worth googling and reading. Pretty sure it was a three part series (like in Aug/Sept/Oct issues so something like that)