First, I sincerely apologize for how badly sidetracked I got (actually, sidetracked from the last sidetrack, which was a sidetrack from other sidetracks ...). I in no way meant to drop this, just got totally tied up in other projects, and work and life. Still am actually ...
I really appreciate all of the responses, amazingly prompt too! (Not like me!) As far as I could, I examined and tried each of the methods. I found a fifth method also - use Geni's tools to find matching names then how they relate to you, and it turned out to be successful, indirectly. This B Davis was unconnected, but had her grandfather listed, and I recognized him as a son of a brother of my grandfather. This exposed another issue in that Davis appears to be her married name, and no tool is likely to be useful for finding someone who is living *and* using their married name! In this case, Davis was not a surname by blood. (I still haven't found the other Davis's that *are* related by blood.)
What quickly became evident was a major flaw with every method - no tool can search for something that is not there! You can only find people that have been entered and are accessible within the database of that tool or site. I don't know how Andreas handles his database, but it's unlikely you can match someone who hasn't been manually entered. For WikiTree tools, you can't find anyone that hasn't been entered into WikiTree, or is hidden. And the same with Geni, you can't find 'what ain't there'. That's a problem because most of us work with multiple tools and databases, and when a name pops up, we can't remember if we saw that surname in WikiTree, FamilySearch, an Ancestry tree or AncestryDNA, on FindAGrave, on Geni, on FTDNA, etc etc. To some extent, that's not solvable, and we'll have to try tools on each one. Perhaps Andreas (for version 2!) can add the capability to build a client database by pulling basic tree info from WikiTree, FamilySearch, Geni, and any other publicly accessible tree, including some Ancestry trees. All he should need is a link to an anchor person from each, and later a conflict handling mechanism. Could be refreshed on demand, when you want to use the tool.