True but SUSE (the enterprise version) is pretty clear about the use of btrfs, just use it for the OS (snapshots), the "data" partition should always be XFS.

AFAIK (though not as connected to Red Hat storage team these days), RHEL is pretty much XFS plus logical volume managers. As I understand it, ZFS was just a non-starter because of licensing + Oracle and the feeling was that btrfs just wasn't quite there.