Halo effect...interesting term. On the French Marans site, it appears most of the featured Wheatens have similar hackles: http://marans.eu/fro.htm#froThe halo effect he shows in his hackles is discouraged in a Black Copper, but I'm unsure whether it's acceptable in a Wheaten.
The standard description for the Wheaten cock in French indicates that the saddle and hackle feathers be uniformly red or reddish-brown without too much "flamme," which literally means flame but I am not sure if that is referring in plumage terms to shafting or to variation in tone along the feather. Alas my college French education was literature-based rather than agriculturally inclined, so not a single one of my classes was on poultry fancy terminology! This is a helpful image from the French Bantam Club's website and I hope it's okay to share it here (the image didn't have a copyright on it) since it labels all the parts in French making it easy to draw the parallels between the French terms and those in an English SOP: