Org mode looks great, thanks for calling my attention to it. For anyone looking for a brief introduction, they have a compact guide[1] on their site that took me a minute to find.

It looks great for coders who are ready to learn new syntax. Though what I'd really like to avoid with Margin is anything that makes the language more complex than it needs to be.

For example, org mode defines headlines as:

    The headlines in Org start with one or more stars, on the left margin. For example:
    * Top level headline
    ** Second level
    *** Third level

With Margin, there's no concept of a "headline." For the thinker, the headline could be represented by any level of the plain text hierarchical tree. And the thinker would then be free to choose (or conform to) any Margin-based app that corresponds with their model. In other words, it works best however you want to use it.

[1] https://orgmode.org/guide/