kchodorow/docs — comment on commit 0b6874fb2320ce01004a49a549fe7556099a5f72
File: source/administration/replica-sets.rst line 138
By kchodorow:

Reconfiguring won't succeed on the remove/added member if the _id changes, leaving it unable to update its config.

2.2 won't care if the _id changes, so you can do rs.remove/rs.add and it'll work.

People seem to like playing with removing/adding nodes, so it's probably a good idea to mention the _id thing. But if you want to keep it simple you could remove the whole thing, it's not exactly a common ops problem IRL.