Dave,
Thanks for taking the time to show us you Gen 2 stationary and articulating thumb. I think they came out great. It's funny you and I were working on similar projects, not knowing exactly how the other's would look.
Our concepts to power the jaws are the same except you used different pivot points than I did.
The other difference is your linkage runs above the dipper stick and mine runs below it.
Your final link to the jaw seems to be a lot longer than mine. How long is that one? Are the main set of pivots connected to each other (where all 3 links come together) or to the cylinder? Do you have a "rest" position for your thumb?
Very interesting indeed, how we accomplished the same thing with the same concept but varying technique. It's great to be an American, isn't it?
Great job.