You must remember though that rsync is part of a larger system. It relies on a transport mechanism (rsh, ssh etc) and many operating systems services (such as inetd, syslog etc). If any of these other parts fail then rsync will of course be affected.
Also remember that rsync comes with absolutely no warranty. It is up to you to test whether rsync is suitable in your computing environment, both before and after the turn of the century.