"But lack of 'slam' and 'drive' is more related to the drive then a platter-mat, in my current experience."
Totally agree.
I can't seem to understand how a platter mat can improve dynamics, slam, and "drive". No matter what mat I put on my Empire or other belt-drive systems, it aint sounding like my Technics SP10. I have smoother sounding DD tables than the Technics but none can surpass the bass dynamic and slam of the SP10 due its powerful motor. I also played with an idler table with an Ashland motor and it has huge dynamic. Again, the motor. From my experience is that small motor small dynamic and if it's a belt-drive even worse, the Nottingham is one example. I do believe changing mats can change the sound and the extra mass sometimes helps smoother rotation but the sonic benefit, if any, is more of a tonal one and signal to noise issue. Again, that's just my current experience. I would love to try some TTWeight mats.
I am, I guess, a "Technics guy" for 20 years. Briefly, I circumstantially became an Empire guy. I missed direct-drive so now I am back to be a Technics guy again, with a vengeance and end up with dozen other direct-drive tables. It's been fun.