In my opinion, I'd say pull out troff if you're thinking about making a PDF, or if you want tables or equations (see http://www.troff.org/prog.html http://www.t

In my opinion, I'd say pull out troff if you're thinking about making a PDF, or if you want tables or equations (see http://www.troff.org/prog.html http://www.troff.org/prog.html). Personally, I mostly use markdown when I want to generate some HTML but don't feel like typing tags by hand, or just as a sort of "style guideline" when writing text files.