The version of rsync bundled with RsyncX has serious flaws. In certain circumstances, which are not fully known, it can freak out and fill log files with garbage until your hard drive is completely full. In older versions of OS X, all user preferences were wiped out if the boot disk got full, so I think it's reasonable to call this problem "dangerous."

There have been repeated questions in the RsyncX forums about this issue, and the developer has said absolutely nothing about it for about a year. This is completely unacceptable.

The version of rsync that ships with Tiger is, as of 10.4.2, horribly buggy. As soon as it is fixed I recommend moving away from RsyncX.