It definitely depends on your platter, and even on your drive system, because different platters and drive systems resonate at different frequencies, and different mats are going to suppress different frequencies better than others.
A machined aluminum platter (a la Technics SL12x0 series) is going to ring differently than a glass, acrylic, or MDF platter. I have a Technics, and to my surprise, found that the thin, slippery felt DJ mat actually kills more ring than the standard rubber one. So I have both of them on, with the felt directly against the aluminum.
Also, the motor noise level and pitch is going to vary according to motor speed, tolerances, and how successfully it's isolated.
A machined aluminum platter (a la Technics SL12x0 series) is going to ring differently than a glass, acrylic, or MDF platter. I have a Technics, and to my surprise, found that the thin, slippery felt DJ mat actually kills more ring than the standard rubber one. So I have both of them on, with the felt directly against the aluminum.
Also, the motor noise level and pitch is going to vary according to motor speed, tolerances, and how successfully it's isolated.