I've got a Stornoway Grey 90 and I live in the Pilbara. I honestly can't tell any temperature difference between the all white mine spec Prado (work vehicle) and my 90.
I actually think that the car is significant cooler with the roofrack on (Front Runner full length low profile). My theory is that it acts like a tropical roof by keeping airflow between the actual roof and the tightly spaced cross slats...

