Kenan,

A QRD diffusor works by having different depth 'wells'. The difference in time for each part of the sound to reflect from these create phase differences and this is what steers the sound in to a wide dispersion pattern. So if CARA can simulate accurately enough to notice the tiny differences i nthe depth of the QRD wells and it accounts for phase (well, it must) then it will work.

However, I am planning on QRDs with wells only 2.5cm wide, and a 23 prime seed. Very complex to simulate.