One of the devs here - totally true, our help docs and landing page don't really show half of what you can do. Help docs have a lot if you dig around though.
Neither have full feature set, or work collaboratively, but nvalt in particular gives a good 80/20.
We export to plaintext markdown that reads well in either, planning export to org mode with enough data for a good elisp hacker to build parity of main features -- will do sooner if we know there are takers for that.
Have seen cool analysis of JSON export in Wolfram Alpha.
Also -- for folks asking about how we're different from Workflowy or Evernote or existing wiki tools
Key claim we have is that knowledge doesn't really fit into the tree structure of a file system (nearly 100% of knowledge management tools follow that structure)
In Roam, you can organize things hierarchically -- using indentation -- but when you link to another page, the paragraph or bullet point where you made that link appears in the "references" for that page.
Pages -- like a page for a person, or a concept -- end up getting a sort of implicit definition from all the other places where you talk about them.
So, a page for Alice or Bob for example has all the tasks that have been assigned to them, and all notes from meetings that involved them.
A page for a concept like [[Paul Graham recommends Clojure]] pulls in all the paragraphs or bullet points where you used the term -- and the bullet points nested below.
You can import any plain text or markdown file into Roam -- we take the indentation structure and parse it out.
Can also copy/paste in any html
Would build a special emacs importer if there was strong need -- but emacs export is so powerful you can also just export org-files into a format that Roam accepts already