The state of the LJ backup software scene is pretty depressing. I think "research" might entail "software engineering" at this point, between the orphaned, but open source, Windows-only LJarchive, Dreamwidth's live importer, and LJbook all copying down comments but all working in slightly different ways.
Talking to the Dreamwidth folks might be a good idea, actually. If we can extend their importer to accept uploaded backup files, and spin off their code into a program people can run on their own computers to generate those backup files, that'd probably be the ideal. *totally lacks the skills to make that happen though*