Welcome fellow aussie. I've had my A90 for over a year now, it's ace.
My GF has an RS265, it's an awesome car.
Here's what I did with my plate:
stock for stock (have both.... well the A80 ain't stock anymore)
A90 was far more savage IMHO. More grip yes, more power, more torque, more compliance.... but also will wheelspin into third in a straight line if you want it to.
A80 felt mushier in comparison - not slow - but mushier.