This reminds me so much of the mass digg exodus of 2010. It's going to be interesting to see how this goes.

The part that was confusing to me is even if I choose “All” when searching for communities, it doesn’t find communities I know exist on other instances. This post helped clear it up for me (I have to search for it by link to add it), so thanks! I am worried this is going to trip up a lot of people though.