Rumor has it that the boot-binding coupling is not as tight, especially at the heel (since the latch- down mechanism for the heel is not as torsionally rigid as screwing it in permanently). But all I (all 145 lbs. of me) have noticed is that my Dynastar ATV is a lot different (both good and bad) than my race skis. The effect would be most noticeable on ice, but the Supermountain is a pow ski, so maybe no difference where you would be using them?
An interesting test would be mount identical skis with the Fritschi and some alpine downhill binding (setting up shims so that the total standheight and ramp angle were identical) and then see if anyone could notice the difference.