Awww why does everyone have to hate on all the single comb girls? You know most good breeders will breed a single comb roo into their lines if they are having the infamous fertility issues which are carried on the gene for the rose comb. Yes, I know, I know, I speak blasphemy, but it works and the likelihood of having a single comb after a few generations is pretty low. Its ok to breed your girls you just can't show them.
I've not yet heard of a "good breeder" who's used a SC rooster, although I do know the that the Foleys of KY specifically advise against the temptation of using one. ("Murphy's Law states your best cockerel will have a single comb." Happened to my March hatch!)
I won't say you "speak blasphemy," but I will question whether you understand the mechanics of an autosomal recessive gene. I am only breeding from RC birds, and am still getting SC chicks, though I could not tell you how far back a SC bird was used. Simple autosomal (fancy word for "not a sex-linked trait") recessives can lurk for generations, and Wyandotte breeding books and articles I've found going back a century talk about the occasional SC chick, and cautioning not to use one for breeding. The specific example is a book published in 1917, "The Wyandotte Breeding and Standard."
Since I have trouble distinguishing "tone" in posting, I will state that I am not trying to bust your chops, or be snippy, just responding to your post to clarify the "hate on all the single comb girls" charge. No hating here, as they can still lay and peck and provide amusement/enjoyment. I just would not use one for breeding *Wyandottes*. That said, I did keep a SC cockerel the other year, and used him for a meat bird project because of his excellent body structure, but he was being bred to Ideal's Red Broiler pullets/hens, and there was no confusion on the chicks. I ran into the lady who bought my Meaties project this week at
TSC, and she still loves her big beautiful rooster. She even likes the erect SC over the RC cull GLW pullets she bought with him, but she is under no illusions about what she has (I printed out a list of all the birds when I brought them up to sell).