Meh you have a link to calculate the difference? As I would be interested. it makes sense, but it's the first i've heard of it. Even the tyre place down here steered me wrong with these rims I was running. specifically asked if the higher profile tyres on my rear rims would affect the attessa the rolling diameters difference was about 5mm they said no. and of course as soon as I left my attessa played up. After switching to my old tyres, with the same profile it settled down back to normal.
Although on the 32 the 4wd system is only part time, it doesn't constantly deliver a portion of torque to the front, which I think the 33 does. Incidently found out on checking again, my front rims are 8 inches and my backs are 9's, and the attessa system works as before when I had 9 inch rims all round.