I'm getting ready to Backup an Xsan Volume for a nuke and re pave going from Xsan 1.4 to 2. I was planning to use rsync, but I'm having trouble remembering the flags to preserve permissions and resource forks and metadata.
I've been using it with Xsan for a few years now, and find it easier to deal with than Rsync. I'm lazy, and it has check-boxes for things like "verify data" and "preserve extended attributes" and "preserve permissions." Also very easy to exclude individual folders or entire paths if you don't want everything synchronized. The speed might not be as good as the command line, but with version control and configurable expiration times on old data it has been really helpful - especially on scheduled daily backups, or new backups I want to setup quickly.
I used it last year for our Xsan 1.4 to 2 migration, and again this summer to copy about 12TB of Xsan data to a new Xsan volume.