Isreal borders both ranges, so dogs from that region tend to carry both genes, Morroco, where I lived for a year is at the far end of the Sloughi's range, has the purest Sloughi's due to geological location, and while there I never saw a feathered one. Like you said earlier, feathered ones did turn up in france, but that doesnt mean they do in the atlas mountains.
Though of course the k.c doesnt mean a lot to the owners and workers of this breed, or type, and there not shy of introducing other good stock into the mix, like greyhounds for example.
Which is something that can confuse the m