As I am aware, Fender wrote this on their web site about the tone control on the Performer: ''This uniquely Fender tone system lets you cut treble without losing gain or “muddying” your sound, preserving your carefully shaped tone.''
While making the video I heard the difference, and I can explain it so that the Fender makes the sound less muddy, and Sadowsky keep more bass whet turn the tone pot all the way off.