Mobiledoc dev here. Mobiledoc is used at Bustle (who funded initial development) on two properties, at Upworthy, Daily Beast, and on several other sites. We're extremely proud this work has also been adopted by Ghost and hope to continue working with them for a long time :-)

One of the benefits of Mobiledoc is that we provide a documented and versioned file format for serialized documents. This allows developers to share renderers for Mobiledoc content. Bustle for example publishes Mobiledoc articles to it's own HTML, to Google AMP, and to Apple News.

Mobiledoc also supports runtime-customizable "cards" for rich content. For example a writer might add a video to an article- but for each rendering environment the runtime version of that card must be different. The cards API allows developers to offer custom editing and embedding interfaces without breaking the general text editing interface.

Try it out and let us know what you think. You can join our Slack: https://mobiledoc-slack.herokuapp.com/ or find me on Twitter as @mixonic.