Thanks so much for your reply. As you are considering DNA testing, here's the particulars for my son-in-law: FTDNA Kit 211910, y-DNA haplogroup E1b1b1a1b - or the shorthand version is E-V13. If you google this haplogroup (E-V13) you'll find an interesting read (or is for me anyway).
Your Floyd research appears to be rooted in source information and for this my hat is off for your work. I have found online source material for Josh's lineage into the early 1800s. For the deeper genealogy I have found posted online family trees (not always reliable), hoping then to locate supporting source material. This is why I mentioned David Floyd only as "reported to be...."Having said that, one researcher has David as one of three brothers who came to America from England; one settling in Maryland, one in North Carolina, and David in Virginia. - with David being born in Wales about 1735.
I'm guessing that as your surname is Floyd, that you are a direct paternal ancestor of the patriarch Floyd in your research. As you probably know, the y-DNA is passed down from father to son. So I would be very much interested in learning if your y-DNA results fall close to my son-in-law's resulst, as Josh is a direct paternal ancestor of the Floyds mentioned above.