No offense, but when I downloaded a sample PDF I expected to see a better formatting. The file is little bit clunky. I think it's not a failure of a formatter, but the design in general. The default markdown formatter in Leanpub works good enough, to a degree when I don't need to think about it.

So, while I understand all the good parts, I am still kinda not convinced it's a better option looking at the final product.