You might save a few $ by droping the S - the 60Cx will do all you need.
Tracks 4 Australia and Shonky Maps should have enought detail to get you happin anywhere in OZ. Yes they are Gramin maps - free..
If you want world coverage I think you'll find garmin is best .. and Bobs maps are getting better with contributions (track logs) from users.
Regards Frank Warner
motorcycles BMW R80 G/S 1981, BMW K11LT 1993, BMW K75 G/S