Just for the fun of it, I'm curious....How many of you change the VTA/VTF when you listen to different mats of varying thickness? I suspect some of the differences you hear may be more assignable to the changes in the VTA than the differences wrought by the mat.
Note, I AM NOT saying there is no difference in the sound that mats can bring. In fact, all of the issues and theories assigned to TT set up to deal with vibration can probably be assigned to TT mats as well.