There's a potential issue with both RTF and Markdown, and it has to do with embedded images, and how they're encoded in macros.
I created some RTF documentation, which on disk takes up 116 KB. I pasted it into a "Display Text" action, and it looked pretty good. But when I exported the macro, it was almost 6 MB.
I really don't know if this is a concern at all, or only a minor concern, or what. And chances are you've already thought of this. But just in case, I wanted to give you another reason to keep this low on the priorities list. I thought I'd let you know.