If we edit HTML we get a fallback to TinyMCE editor. So we can just set MarkItUp as default editor and edit everythink we want with the proper editor.
MarkItUp Editor with reStructured Text and preview on bottom
By now Markdown and ReStructuredText works fine. And it has nice integration Plone to put in images and links like in TinyMCE.
collective.markitup does not provide any additional markup languages. It is just a editor you can use to edit Markdown, ReStructuredText or possibly any other markup you can choose in Plone's Markup settings control panel. By now Markdown (text/x-web-markdown) and ReStructuredText (text/restructured) works fine. And it has nice integration Plone to put in images and links like in TinyMCE.