I'm curious about the choice of LaTeX. According to the article, it was about controlling the layout. I did something similar [0] a few years ago, but my "stack" was Markdown + Pandoc; converting Markdown directly to an epub with Pandoc was more than enough, but for the paperback version I converted the Pandoc to a LibreOffice document with a custom template; this let me do all the fine-tuning for the styles, paragraph flow, etc.
I wonder if you tried this and decided LaTeX was better, or if you went for LaTeX due to your previous familiarity with it. I have the feeling that for my novel it would have been overkill; did you get most of the value by having precise control of the layout of the images?
(btw, the "Power Move One – Conditionals" anchor seems to be broken)