Phil if I understand you right about the metal verses the plastic hook up to the fixtures insofar as being safer one over the other. My answer is that if the service is properly grounded including the equiment grounding conductor. there are no difference.In a residential dwelling where there are metal water piping the nec req us to run a EGC within 5' of the service.
Far as the GFCI are concerned everyone should check those on a regulary monthy basis.
Wayne
