Totally agree. The B/B/S gene modifies what would be the black feathers to a blue or gray color. You wouldn't see any black feathers if the B/B/S gene were present.
Pretty much in line with NatJ except I don't think you have any actual Blue genetics in your flock. As he said in that other post a RIR rooster over an Australorp does not give you blue genetics. I don't think you'd see any blue chicks. Unless some of the sex links offspring have white tails...
Black is pretty dominant so black roosters tend to father black chicks. White is a crap shoot. Some white roosters pretty much father white chicks but some can father about any color or pattern. I'd avoid black and white roosters if you want a variety of colors. Red is relatively recessive...