Hi Cando! :*)
You're right about the A website but it's still got plenty of good nuggets IMHO

Sapphire mentioned Michael was born 1872, so the SA ref sounds promising!
I see in the Australia Birth Index there's also Michael Metz b. 1871 (Robert, Amelia) Berrima, New South Wales.
Also, Sapphire (wrt Michael's dad): I also found these 2 pieces, there's links so you have a couple more websites to add to your research arsenal.
According to the NSW State Records (
http://srwww.records.nsw.gov.au), there was a certificate of naturalisation issued:
Name: METZ Robert
Native place: Germany
Date of certificate: 10 Aug 1868
Ref: 3//88//[4/1202]//130
I also saw this in the online Aust newspapers site:
(
http://newspapers.nla.gov.au/ndp/del/article/14390298?searchTerm=%22robert+metz%22)
The Sydney Morning Herald - Tuesday 11 June 1901
ROBERTSON, Monday
Robert Metz, stonemason, a resident of Moss Vale died suddenly yesterday afternoon while driving in a sulky at the junction of the Robertson and Burra- wang roads. Deceased was accompanied by his daughter at the time.