Archive.org doesn't seem to be archiving articles from the new forum properly, which would be really valuable in my opinion. When I consult a post on Archive.org, it briefly shows up, and then the post disappears, and all I see is "Sorry, we couldn't find what you were looking for." For example: https://web.archive.org/web/20181113212118/https://forum.effectivealtruism.org/posts/4r3ZpiEoWft62yPwv/crohn-s-disease.
Credit where credit is due: we are deeply indebted to the Less Wrong team for letting us use their codebase and providing assistance with the transformation and migration.