Winston
I know you already have a large list of things to test, but I'm also very curious about the role that stropping can play in edge longevity.

Some of the discussion about electron micrographs reminded of the images on the scienceofsharp blog. https://scienceofsharp.wordpress.com/

Looking at some of the posts there, it appears that stropping (with an abrasive-loaded strop) can improve edge quality without making the edge too convex. The pictures from the blog suggest that stropping can create a more refined edge, and also add a micro-convexity, which may increase edge longevity.

The blog is mostly about straight razors, which have a different stropping technique from that used with woodworking tools, but I wonder if woodworking tools can similarly benefit from stropping. If so, then it would be good to know, especially for people like me, who can do a decent job sharpening, but aren't experts at sharpening technique.

I know there are a lot of potential variables with stropping, and I don't think it's worth it (yet) to try a bunch of different ways. But if it turns out that a simple stropping technique leads to good results (without creating long-term issues like a heavily-rounded edge), that's a valuable piece of knowledge to have, because it can be put to immediate use, and because it could also lead to more exploration about different techniques.

In short: Does stropping improve edge longevity? And can a loaded strop serve as a substitute for a fancy finishing stone?

I think the work you've been doing is really valuable. There have been endless debates about sharpening and steels; if 1% of that energy were spent on objective, repeatable testing, like the kind you're doing, then 99% of the debates would be irrelevant. The thing is, dropping into a sharpening debate and arguing is easy; doing science and communicating it is hard work, and in this case, at least, it's falling on one person's shoulders.