I'm very particular about how I want certain parts of the book to work, and with Leanpub there was a lot of random tweaking of Leanpub-flavored Markdown to try

I'm very particular about how I want certain parts of the book to work, and with Leanpub there was a lot of random tweaking of Leanpub-flavored Markdown to try to please the parser. I'd change a thing, press build, wait 9 minutes and check to see if that fixed it. In particular, woe is me if I wanted to use a mathematical formula. I like that with Softcover I can use a local build system and can fall back to LaTeX (well, PolyTeX) to give me much better control.