Journalling the files themselves would be redundant in XFS because new files and changes to files are Copy-on-write. The new sector is written first (even if the file isn't growing) then the metadata is updated. If any part of the write fails the metadata will be pointing back at the original sectors untainted by the failed write.
Don't go setting filesystem requirements like how Journaltastic it has to be, unless you know the limits of usefulness and relevance of those requirements. If you're going to set requirements don't base them on the inner workings of the filesystem, but what you need to do with it. (Survive power failures without filesystem corruption) When it comes time to choose a filesystem, pick ext3. It's just the right choice unless you think you need more than 8TB of filesystem space. XFS can do that, but you're better off using multiple ext3 filesystems, and symlinks.
Ext3 it (at least as of today) Linux' filesystem. Period. There are thousands of choices. Only one right one (ext), and ext's current extremely stable version is 3.
That said, if you need a sql driven filesystem, try fuse-mysqls: http://sourceforge.net/projects/mysqlfs/ http://www.linux.com/feature/127055?theme=print
Storing its data in mysql, you can use mysql's native high availability clustering to keep multiple instances on multiple machines in sync, at all times, without scripts, inotify, or a SAN. Just don't count on any degree of performance.