Dr Saltzman says he can migrate 3 years of old posts and believes he can also make them usable for continued posting of new comments. I would say this is a major reason to migrate the old posts, to keep them usable for continued new comments.
Remember in all of this, the choice of using LLS is not just for us, but there are about a dozen LLS Discussion Boards since LLS provides a place for many L&L type Discussion Boards. We provide a certain amount of leadership on issues interfacing with LLS, so we would be abandoning the others.
Also, if we leave then there will still be a CML L&LS Board, but without any people capable of providing help. I don't think we should abandon these future patients.