ACLs have the potential to be extremely useful, but just be careful - it looks like they aren't quite ready for prime time in OS X:
http://www.macosxhints.com/article.php?story=2006102912402560
I had noticed something similar with '
rsync', but since so many problems had been reported for the new 10.4 version of '
rsync' (ie. with support for extended attributes and resource forks) that I assumed it was '
rsync' that couldn't deal with ACLs. But since '
tar' also is affected, it might be a more general problem with the interaction between ACLs and any of the new updated resource-fork aware command line tools.
Worst case - when performing an incremental back up from a source on an ACL enabled volume to one on a volume ACLs not enabled may result in the loss of every single resource fork in the destination folder. Not just a failure to preserve them on the files that differed in the incremental backup, but an active stripping of resource forks from every file already in the destination.
This could potentially be an issue if anyone is using any sort of third party software that is using '
tar' or '
rsync' or any of the other affected tools under the hood...