A new importer is available which takes the JSON file from the RoamResearch export.
Note that this feature is currently only available in the .JAR distribution format, not with .MSI or .DMG.
Update: See also this blog post.
Update 2020-01-19: For my note-taking workflow, see https://x28newblog.wordpress.com/2017/06/14/seven-habits-of/ number 4-6. Thanks to @conaw for the hint.
Update 2020.01-20: Here https://youtu.be/a7XbgD4VVa4 is the video of my workflow that @conaw asked for.
Update 2020-01-21: Here http://condensr.de/2020/01/21/note-taking-video/ is the transcript and description of what you see in the video.