Dear Colin,
Thank you for your response. Just a couple quick comments:
1. "I believe a paradigm shift in cosmology ought to come about from the failure of a second order test of general relativity in an experiment such as the proposed LATOR mission."
I hope that a second order test of GR will be performed soon. I suspect that most people are too tied to the expectation that any new test will just end up confirming GR, but since at this point we really do not know where its boundary lies, I would be more flexible in my expectations.
2. "Under this assumption, arrival times would vary because of differing path lengths. The variability of arrival times might be interpreted as variability in the speed of light. "
This is exactly what I meant when I was asking about a "change in lightspeed". My expression was sloppy and I thank you for correcting me. Like you, I would not expect the constant c itself to change based on what you presented. Again, I mentioned this because it seems to me that it might be a way of testing the tied light hypothesis.
3. "The section on gravitons was particularly interesting. I can't help wondering if gravitons might involve the quantum energy Hh."
Yes, this interpretation of gravitons is totally unexplored since it completely goes against the current paradigm. If I did not already have all my hands full with my current research program, this subject matter is what I would work to develop. While I do have some ideas about how I would go about exploring this, I must admit that the connection to Hh is not obvious to me (unless perhaps you mean the connection to gravitons as usually conceived, spin 2 particles traveling in space at c?). Care to elaborate?
Best wishes,
Armin