Bart, thanks again for all your great research and insights, and for taking the time to explain them at length. (By the way, I don't think you're wasting words.)
The only part of your findings that doesn't completely jibe with my own (admittedly much more sloppy and intuitive) findings is where you say that a blue will get the edge keener than the coticule can. In my experience, a coticule with very light slurry keens up a razor very quickly, and takes it further than what I can do with my blue. But this may be a distinction without a difference, because your fundamental point I agree with: versatile as they are both as cutters and polishers, coticules do not in themselves bring the razor to ideal keenness.
My escher (first with slurry, then without) seems to be able to get that last bit of sharp much better. So my basic standby approach is to cut the bevel with a DMT 1200, polish it with the blue+slurry til it cuts arm hairs, polish it with yellow+light slurry til it quietly fells arm hairs, then polish it with the escher til I'm bored, impatient, or the phone rings.
If things don't work out with the swaty, I'll go back to this. But your analysis makes so much sense to me, and integrates so many odd observations I've made along the way, that I want to see if using the swaty after the blue, then using the yellow with water only, and stopping there (no escher) gives me comparable or maybe even better edges.