I am under impression that OpenBSD will be shipping rsync version 3.1.1. While backing up one of OpenBSD 5.5 servers rsync 3.1.0 to FreeBSD 10.0 rsync 3.1.1 with rsnapshot I bumped into a bug which causes rsync to terminate communication. One way to "fix" it is NOT to use option -z.
It seems that bug doesn't affect communication with earlier versions of rsync as I had no problem backing up bunch of Red Hat desktops to the same FreeBSD storage server. I hope it will be of some help to people. Predrag