I wish
@qaccy above added 1 chapter 16 tech, and it added 18 points. Another city added 11 and 9 chapter 16 techs in two weeks, and each added about 24-31 per tech... These increases are definitely correlated with base Spire SS itself (meaning cities with higher SS get bigger increments), that's how it works for pretty much all parameters so far. Tiny cities get tiny increments on AW levels, research and expansions etc.
Meaning in your comparison with hondamike, Mike would be getting bigger incremental increases on AW levels on average, and in limited data that I've seen so far the same applies to research impact.
6.9 parameter was used to fit the most cities with chapter 15 data. As I already mentioned, constant increases per AW level is definitely not how the actual calculation works, but it was a good approximation for specific set of end-game cities. Difference between 6.1 and 6.9 over 100 AW levels of difference is only 80 SS points, which was well within the accuracy of the end-game model. This model does not work for cities other than the ones at the end of chapter 15.