I 'know' David Martin Sears; that is, he's in my personal database as a distant cousin. David's grandfather, Samuel Sears (1769-1846), was the brother of my ancestor Frances Sears (who married William Imbler), my 4th-great-grandmother.
I'm very into DNA and therefore working on mapping chromosomes. I have several people with whom I share DNA that are descendants of William Imbler and Frances Sears.
Have you uploaded your results to Gedmatch.com? If not, I recommend you do so. You then can compare your DNA against people that have tested with any of the three testing companies -- Ancestry, 23andMe, FTDNA -- and see exactly what segments you share. I could then compare your results (if you list your Gedmatch ID #) against the known Sears/Imbler descendants and see if you match any of them.
On a much more interesting note, I just searched for you on my mom's DNA test (my Sears line is through her). Guess what?! You are sharing DNA with my mom! I clicked on the link for shared matches between you and my mom, and two other people show up: jleniger and and R.S. And they both descend from David Martin Sears...
Have you put together a 'purported' family tree on ancestry and connected it to your DNA results? If not, you might consider doing so. That way, you could see who else matches you that traces back to this Sears line.
As far as other lines, on AncestryDNA, you can click on the link for 'shared matches' (like I did), and it will show you people that are matching both of you. Then you could look for common surnames amongst those shared matches to get ideas of possible ancestors.
If you need help, feel free to drop me a PM and I'll see what I can do. You just might be a distant cousin of mine!