Fred's Hens :
First, the Barred Rocks were bred, in part, out of the Dominique to begin with, way back when. They've always been related. The Barred Rock was made, IIRC, by adding some Cochin and other things. Anyhow, the Barred Rock is a derivative of the Dom to begin with is the point. The Dom over BR would produce nice birds taking on blended characteristics of both. You would still be able to sex them at hatch the way you do both breeds now, by the head spot.
The Dom has yellow legs. Non yellow legs would come from some wrong things in the recent breeding of a particular bird. It's sure sign of not being a BR in purity. Lots of folks breed sub-standard birds, call them BR and sell them. Doesn't make them bad birds, just not quality stock.
Not disagreeing with what you wrought but only clarifying it.
The Dominique that was used to create the Barred Rock was a different breed than the Dominique we have today.
Back when the Barred Rock was being created the word Dominique referred to a pattern and not a breed since then we have broke down the Dominique pattern into Barred, Cuckoo, Crele etc..
Dominique (Dom) Gamefowl
(not my bird)
There was even a Dominique Leghorn
http://books.google.com/books?id=33...Q6AEwAQ#v=onepage&q=Dominique Leghorn&f=false
Also the Cochin that may have been used in the breeding of the Barred Rock was probably the Cochin China fowl that differed from today's Cochin.
Chris