Have you tried using the list-table directive? I find it's a much easier way to create tables - it's based on writing indented lists which mirror the logical structure of the table (i.e., table / row / cell), rather than trying to produce ASCII art.
All my doc is in Sphinx so I play it safe, and all directives need to be supported in whatever version of docutils and rst2pdf are installed across the various developer machines. So for the moment I am stuck with ascii art.
rst2latex has worked very well for me. The current version has math mode. I've occasionally had to write some custom LaTeX to get things like natbib to work, but it's largely been problem-free.
