RSS is going to be one of the first things that is noticed to be gone, I think.
RSS sorta works. I was able to make rewrite rules for EUforum/* but exclude when the module was RSS. Thus, all of EUforum redirects to the new forum (and correctly rewrites from valid URLs to valid URLs) except for RSS. So the old forum still dishes out valid RSS feeds. Thus, this has become a lower priority task.