“What's most interesting is the description of how the original 70mm 6-track mix for Star Wars was derived from the 4-track master. This is basically what I had assumed, but was unsure of. What it means to me is that the perceived "holy grail" of the 70mm mix is not that at all, and that for home theater, a mix derived from the 4-track master should, in fact be better. Now we know that the '93 mix combined some of each, with additional effects.”
I re-read the excerpt and can find this stated nowhere. It seems clearly outlined that the basic track for the ’93 mix comes from the 6-track print master only.
I also disagree with the notion that the 70mm and 35mm sourced a common 4-track master for their respective mixes as has been posted elsewhere (I can think of several comparative examples that demonstrate this). It is my guess that both came from common stems, but that the final mixes of each, reflect different choices in presentation.
I am currently cooking up the side-by-side “93 mix vs. 70mm theatrical” audio file that I mentioned previously. After that, I think a similar “original 70mm vs. original 35mm” would be worthwhile, to explore the issue.