I know this is a rather old post but I've just recently been looking into my family history with use of Ancestry and have found a few of your posts about Johann Eyl throughout the web. He would be my 5x great grandfather.
I just recently got the results of my Ancestry DNA and according to that my genes are 100% European with 60% of that coming from Western Europe. So that seems to really go along with the Hessian soldier story. I know I have read a few posts by people saying that they don't believe that it's really true.
Before reasearching any of this everyone in my immediate family always said that Iles came from an English name so it was really cool to read everything you found and learn that I'm actually German so thanks!