just throwing this out on the odd chance any new information exists out there...I am quite content with the information we have and count myself fortunate. I assume we were of the laboring masses, or even slaves, to explain the sudden absence of information.
My surname is Mills. We did the DNA service thing a few years ago, but seems to have hit a wall around 1650's.
While the strongest DNA matches are McCullough/McCulloch, Boyd, McCracken, McTaggart/Taggart, and Ferguson, the access to church records is what revealed names and dates. We assume, since at some point we became Covenanters, the origination is some Presbyterian church in Irvine, Ayrshire.
FWIW, our haplogroup is I-L126 (I2b1a1), and I'll offer all info I have available, starting with our first generation in America:

James Mills b.1745 Ayrshire, Scotland, d. 17 October 1823 Chester Co. South Carolina USA
Isabella Leslie b. 4 March, 1759 Rothes, Morayshire, Scotland, d. 6 January, 1841 Chester Co. South Carolina USA
His parents:
James Mills b. 3 December 1701 Greenock, Renfrewshire, Scotland, d. ???
Ann Baird b. 9 August 1702 Riccarton, Ayrshire, Scotland, d.???
His grandparents:
Thomas Mill b. 19 August 1677 Liberton, Midlothianshire, Scotland d. ???
Barbara Jamison b. ca. 1678, d.???
His great grandparents:
Johne Mill b. ca. 1650 - Scotland d.???
Beatie Reid b. ca. 1650 -Scotland d.???