I would suggest: Add a "render as" combo list (drop down) to the client (i.e. select "render as Github flavored Markdown"). Add a "edit in external editor" button (i.e. "edit in Vim"). Profit by making your hardcore (and loyal) users happy. Alternatively: Wait until some enterprising full-stack developer and designer combo pair up to build your clone promoted via Kickstarter. It certainly won't be me; I'm happy with my day job and I know how much work this would be. That said, how long until some hungry and talented team catches on?