I use Pandoc [1] to write in Markdown and then have it converted into LaTeX. There's been some bumps, but it seems to let me have (most of) the best of both worlds.

This post was the inspiration for using it: http://kesdev.com/you-got-latex-in-my-markdown/

[1] http://pandoc.org/

LaTeX is more like XML or HTML than Markdown or rST.

One could duplicate the functionality of LaTeX with a superset of rST or Markdown. Case in point: Sphinx. That's essentially writing your documents in a combination of rST and Python.

I have written all of my books (Treading on Python, Pandas, etc) in restructuredtext. I have tools that convert said markup to epub and LaTeX[0].

There is some learning curve, but you can get LaTeX out of rst from docutils, Sphinx, or my tools.

0 - https://github.com/mattharrison/rst2nitrile

I switched from beamer (LaTeX) to markdown + pandoc for that very reason. Beamer was just too command heavy to be useful for quick slides.