I asked Chis Rice if using a NAS as a source, with ZFS for the redundancy and self-healing feature, would have any deleterious affect on sound and he suggested that it very well might introduce some artifacts. This being the case, using it for a secure backup with a USB drive as the main source seems like the way to go. ZFS, notwithstanding its benefits, does not remove the need for a backup anyway, so it all works out.
PS. This site's spell check feature suggested I change "self-healing" to "slaveholder." I'd rather not!