Hi John!
The Developer branch is the safest one, it has the tested design and it works!The other branch, “Design Update” was created by me time ago and contains an updated design that I didn’t test yet. If someday I’m able to test it and it works, I’ll merge it to the Developer branch.
So, you are in the right way!
The extra motor you noticed is used in the 2nd articulation, that uses the force of 2 geared motors to move.
Hope to see photos of your Thor soon! 🙂