[syngrog66]

sounds like a net win. Markdown is a superset of plain text anyway. You could make Markdown the "source" format for each page and then the web server decides at last second which MIME type header to return based on requested suffix. But even if they request .txt the page body could be identical to the md

I have a few WIP books where Markdown is my source format for similar reasons. I then use pandoc to render to txt, html, pdf, doc or epub as desired.