A ton of fixes since beta1. Especially the new dsync and the replication server related to that should really work now. It also works correctly now for shared mailboxes with private \Seen flags. And the replication server uses incremental syncing after the initial full sync, so it should be pretty efficient also.
I've only two things left to do before v2.2.rc1:
1. Implement dsync to work via TCP and TCP+SSL sockets. This is pretty easy to do actually, since it can use the existing doveadm-server to start up.
2. Read up all the pending mails from Dovecot mailing list and fix up the reported issues. Actually I guess most of those are for v2.1, but still I should get around to it. :)
There shouldn't be any major bugs left, so I'm expecting v2.2.rc1 out in maybe a week or so, hopefully followed by the final v2.2.0 soon afterwards. Please test and report any bugs found!