I actually favor an extreme color contrast, with a super light male... Also, slightly lighter females helps clear up any excessive dark cast on the feet of the females.
I have seen two variants within the light colored birds. Some were contrast will well developed and some where contrast is soft / fuzzy giving a smokey look. It is hard to discern them most of my photographs. Bird shown above has the smokey look.
I do not have any darker females as adults. Plenty as chicks and juveniles but the fade out as they grow. This make early culling based on coloration not productive for me.
The type is the most expensive problem as it does not show until birds sexually mature. It is kind of cool watching type come in on the male side. Process is behavioral and takes only a couple of days. Once in it stays in. Later I will post bird above as he goes through transition.