What's your opinion on doing it not "a la LaTeX" but actually in LaTeX? I mean, for writing the bulk of initial core text it's not much different than Markdown, but when you do get to the typography stage then it has all the things needed for the print layout.
Never written a book, but I have written a few reports in Latex, and I would say it is a miserable experience. Slow build times, horrible error messages, and so much markup for everything.
I have taken the stance that all writing should happen in Markdown/Asciidoc/Pandoc/whatever minimal flavor you like and once content is complete, then port everything to Latex if necessary. Pandoc can spit out a reasonable .tex file you can then massage into a final product.
I never wrote a book, but I wrote my dissertations (100+ pages each), resumes or any other article in Latex, using Miktex. It wasn't the best experience UI-wise and until I learned proper Latex (which I now have forgotten) the error messages were shit. But the build times with quick builds and splitting stuff in chapters was actually a great experience for me. Maybe it's 'rosy retrospection' or I've been out of the loop with the current happenings in typesetting but if tomorrow I need to start writing a technical book, I'd still pick Latex.
