Thank you for posting about this, Billy. It helped me to think through some things.
Many in my paternal grandfather's line were early North Carolina coastal plain settlers/planters. I have no evidence that any were known as Melungeon or lived in the hills, but if the family trees of cousins identified with autosomal DNA tests are a good indicator, then we may at minimum have some Melungeon cousins (in particular, I see pockets of Mullins and Collins families showing up in some trees, and I have a vague sense that endogamy is plaguing my analysis in my paternal grandfather's maternal line).
So having a grip on how/when/where Melungeons came to be a separately identified group turns out to be something that feels relevant to my family research. Their story -- what we know of it -- is certainly a vital and fascinating part of the history of Appalachia.
EDIT: the part of my family that I believe to be cousins with these folks is a part that I don't know very well. They get semi-lost between Princess Anne and Surry County, Virginia and show up for real in the coastal plain. This is due to record loss, of course, and it does put a real damper on being able to track down the origins of Melungeons as well, since they seem to have become considered amongst colonists as a distinct group during the "dark ages" of lost records in Virginia.