It can be confirmed as a Sandman with all the information and viewing the correct areas of the actual car without a HHS report.
But a HHS report will confirm if the tags and chassis are a match and if these tags were once a Sandman. It will ever confirm that the shell is original.
It will also certainly help if you ever wanted to sell or prove the tags history. Only Brisbane built Sandman's had the XX7 on the actual plate.