Oh, no. Now you all have me doubting... I had 4 chicks (2 marans, 2 jerseys) and was 90% sure of sex by about 3 or 4 weeks due to feather development. The suspected roos (one of each breed) then sprouted combs, etc. and continued to look more and more roo-ish as the weeks went on. The other two just kept growing and have demure little combs. I got rid of the jersey roo at about 7 weeks and the maran roo at 8 weeks and then...pullet (maybe) starts crowing!
If she turns out to be another roo I will be so upset! It's so hard to get rid of these little guys that I've raised from chickhood! I actually don't mind the noises my chickens make, even the crowing, but DH doesn't like the crowing and is concerned about the neighbors.
I'll try to post some photos this weekend to see if that helps with gender identity. Thanks for your responses.