Works ok for me.
What happens is only that the side of the tire have a different look. I have -not- tested highspeed (less you consider 140-160km/h as fast) driving with it.
Pigfords warning is important!
In Sweden our insurances are not affected by tire choices. Here they only look at the condition of the tires, not the size, not the make, nor the model.
You do need to check with your Australian insurance what their fine-print says/reads.