dovecot - Mar 2015 - Upgrading a dovecot director configuration?

Is Dovecot Director compatible across Dovecot versions? i.e. 2.0.x to 
2.1.x or 2.2.x? I have a 6 host cluster in a director configuration 
which is getting somewhat aged, but it would be very beneficial if the 
director hosts could be upgraded seamlessly.

Is such a thing possible, or will their be compatibility issues? Would a 
workaround be possible (i.e. migrate to a user system which enforces 
proxy destinations by another means, then do an upgrade?)