I wouldn't listen to that industry body. Most of the Aussie media has a vested interest in saying how great an investment property is.
I've been renting in Sydney for 5 years and find that rents/vacancy rates are extremely seasonal.. Everyone seems to want to move in the summer, you get a great pick in the winter. I've also found, that over 5 years rental prices are pretty stable, I wouldn't be surprised if the loss of LAFHA has had a knock on effect on the market.
I would be interested in seeing the same stats over a couple of years, rather than month to month.