I apologize for not getting back to this sooner. Buff is one of the very challenging colors to perfect. Those babies looks great so far and should be a great start for you. Buff plumage should be an even shade of golden buff throughout the entire body. The APA describes buff as "a medium shade of orange-yellow color with a rich golden cast; not so intense as to show a reddish cast, nor so pale as to appear lemon or light yellow." For males the head, neck, hackle, back, wing bows and saddle should have more luster and for hens the hackle will have some luster. Their underfluff should closely match the surface color and should not be significantly lighter (which I have seen as a common problem). As with any pure plumage color, it should not have other colors present. White and black are common issues with buff, as well as blue on occasion - depending on what folks used in their breeding history. White is often more difficult to resolve than the black. The presence of black speckling (often seen as "dusting" in the tail/wings) is not terrible and can be used if matched up to the right "clear" partner to improve buff offspring coloration. I hope this is somewhat helpful.
Jody