Hey dude. So the wole deal with the roilling diameter is because the attesa system engages when it senses 5% or more rear slip in the rear wheels (ie. rear wheels turn 5% more than front). So as long as the rolling diameters are the same all should be good and act as normal. So the width shouldn't affect the system.
I haven't got new mags yet so I can't speak from experiance. But knowing how the system opperates I'd say it won't affect it. When i get mags im planing on more dish at the back.
On a side note, i noticed that the attesa system was engaging more often simply cause of the diff in tyre preasure in my tires, as diff in pressure results in a diff in rolling diameter.