That shouldn't have broken communication. Version support in this case has more to do with Airwave management on configurations -- there's parts which Airwave claims are invalid.
I have two clusters talking to Airwave with 4.0.0.1 running.
I haven't had either stop communicating, but I did notice that after upgrading to the latest code, it took quite a long time before the communiation was reestablished. (30-40 minutes)