What I have been trying to say, particularly with my Harbeth speaker enclosure analogy, is that in my very humble opinion trying to make a 301 sound "airy, transparent, neutral, fast" et al is trying to turn the 301 into something that it is not. Why would anyone take an Audi R8 and install a lift kit and all terrain tires on it? If you want airy, transparent, neutral, and fast, any number of current era TT designs deliver those qualities in spades.
The 301 as a result of its design has a more relaxed truth of timbre and tone character. The powerful motor coupled with original very light platter also gives it "snap" to transient's and a strong sense of propulsiveness (my spell check denies that as being a word), but without sacrificing the relaxed overall touch and tone.
Why not play to the strengths of the design rather than ameliorate them as if to mimic a modern sophisticated belt drive or DD table?
In my case I did, largely out of blind luck and intuition, substitute a heavy duty all- brass bearing assembly and the Steve Dobbs alloy with copper top platter. At one point I was using the Classic HiFi brass platter that weighs 12kgs, nearly 25 lbs.
https://www.classichifi-shop.co.uk/product/brass-platter-20-mm-oversize/
I much prefer the sound of the Dobbs platter. The heavier platter eliminated all sense of excitement to the sound. How can this be, one might ask? It is rotating at the very same speed and with all that inertia it ought to sound every bit as authoritative. I have no answer. Except that maybe just maybe the resonance of the all brass platter bouncing back through the LP and back to the stylus does something adverse to lively sound. And maybe just maybe all that mass and inertia can not overcome stylus drag and it's effects whereas letting the powerful motor exert itself through a relatively light platter overcomes stylus drag.
And yet another factor is the inherent added friction of a very heavy platter on the bearing assembly.
All any of us can do with the 301 is experiment. If a slate plinth mated with the 301 sounds the way you want it to sound I can not argue that you have made a bad choice.