Does it seem to work qith the Redhat confifurations listed? Yes.
Have I really tested it? No. And I'm unlikely to say "yes" until one or seven things have blown up on me.
In the long run, I think XFS will be an excellent addition to the stock kernel offerings. Right now we're in a situation where XFS is a part of niether the main kernel tree nor any standard distribution offering. You will have to balance its possible benefit against the maintanability of your particular installation (or, more likely, installations). As an aside, my preference is currently for BSD operating systems that make use of FFS over Linux distributions, if only for reasons of stability.
Also, neither ReiserFS nor XFS seem to provide much perfomance benefit to database applications right now -- or at least no more than FFS with soft updates does. The performance gains from hashed directories barely affects the small number of files used in openacs/opennsd/postgresql. As for the reliability factor of a journaling filesystem... that has yet to be proven with these implementations and this particular set of software.