I will use it for shoulder simulations. 3 DOF (actually more, but to start with). IK-like problems follows, since I’m also making a UI where you grab the hand and twist the arm around, until it dislocates (due to injuries on the humeral head and glenoid. Mesh surface collisions involved).
So yes, I will need to apply all the math I can force myself into. 
Thank you very much also for the last example. You already guessed why SLERP is of interest in this context.
I will also have to convert (series of) angle and position data into euclidian ditto’s, both World and CPlanes, oriented to the skeletal joints involved (this to be recorded as simulation results).
This is only one example (of several examples) of why Bongo fails to serve my needs - I cannot log, or record, the positions and orientations while in motion (I needed it for another purely “mechanical” project as well but… never mind). Nor can I script-feed Bongo with motion paths. And thus it cannot produce the “research data” (nor log-data for post-op analysis) which I’m after.
But with GH I can.
In short, I will have to make my own IK Solver. (therefore, hints on existing .NET libraries for rigidbody IK chains is also welcome, saving me time… ).
So detailed output data is one reason to why I need access to source code at all times. It follows that cheating isn’t an option. 
(so, it’s not that I dislike existing plugins, no no, I’d love to jump fences, but closed source components just don’t “let me in” so to speak).
Have a good one.
// Rolf