I use a Funk Achromat on my 1210 M5G. I haven't tried the thick Technics rubber mat though because my table only came with the felt DJ slip mat. I was using the felt mat in combination with rubber drawer liner previously and the Achromat is an improvement over that. Current the rubber liner under the Achromat provides the best sound.
As to why mats change the sound of a table, I think that they all affect damping and resonance to some degree. Small vibrations from the bearing, platter, and air/speakers can travel through the record and into the needle. Because the principle of operation of a cartridge is on such a small scale, vibrations tend to be more damaging in a turntable setup than in digital. All I know is that mats do alter the sound to a degree that is not insignificant, for better or worse.
As to why mats change the sound of a table, I think that they all affect damping and resonance to some degree. Small vibrations from the bearing, platter, and air/speakers can travel through the record and into the needle. Because the principle of operation of a cartridge is on such a small scale, vibrations tend to be more damaging in a turntable setup than in digital. All I know is that mats do alter the sound to a degree that is not insignificant, for better or worse.