You will be able to setup a filter which will allow you to choose which forums you want to see all new posts from. That way you can filter out The Eddy (or Snowriders, etc) and only see the new posts from the forums you want.
Also, we will not be loosing any posts and we even have some backups of some old forum software that we will be trying to restore. The idea is that old posts (Beta, historical flow info, etc) can be useful information. So we will try to get back as many old posts as possible (still need to test that import).