In my experience, the version of rsync included with RsyncX definitely does not have this bug. I use it all the time and have observed no problems like the one I described.
With the RsyncX version the command you'd use is:
rsync -a --eahfs SOURCE DEST
This should be equivalent to "rsync -aE" with Tiger's stock rsync.
In my usage the modification dates are correct, both for copying to a different drive on the same system and for copying to a remote system over ssh.