I swapped some coin with Purple Penny and he did a blog on the medallion and he is querying it at Perth Mint. It will be nice to have a follow up from Perth Mint. In the mean time, this is the link to the blog. http://www.australian-threepence.com/coin-news/perth-mint-off-metal-trial-strikes-what-are-they/
There is also some information on the Koala Store display/trial strike. I think Rooney666 asked before.