[ceph-users] In theory - would 'cephfs root' out-perform 'rbd root'?

On any given a properly sized ceph setup, for other than database end use) theoretically shouldn't a ceph-fs root out-perform any fs atop a rados block device root? Seems to me like it ought to: moving only the 'interesting' bits of files over the so-called 'public' network should take fewer, smaller packets than the overhead associated with whole blocks that hold some fraction of the 'interesting' bits? Does it work that way in practice?