Once you try it, you're never going back. Snapshots are made for things like system administration. Upgrade borked your system? Just rollback.
Want to use the last version of your firewall config? I wrote a utility you might like to try, httm[1], which allows you to restore from your snapshot-ed unique versions.
If you like ZFS, then trust me you have to have ZFS on root.
I would also say Ubuntu is probably the better choice for Linux ZFS, as CentOS seems to be lacking good support.