2020 update : JC Verdier La Platine

Ledoux, You have a fine turntable. A small, low torque motor was used because you do not want it interfering with the steady rotation of the heavy platter. It adds just enough torque to keep the platter spinning. If you remove the string and spin the platter you will able to cook dinner waiting for it to come to a stop. Yes, you want as little tension on the string as possible, too much and the platter starts influencing the motor!
The platter slows the motor down, it fights to catch up to speed and overshoots and as you have noticed you get wandering speed. Using the SOTA drive system will improve speed accuracy for sure but I am not sure you will hear a difference. Keep your feet as they are. Your plinth is just fine.
The SME V is a fine arm but you will need to add some mass for most MC cartridges. People will complain about the arm having poor bass because they fail to do this but set up correctly you would be hard pressed to fine a better arm. The only arms I would desire above it are the Kuzma 4 point and the Reed 5T. The 5T in particular is very intriguing. It is a brilliant design. My hat is off to those guys.
I will never own a DD turntable. Putting an oscillating magnetic device under a phonograph cartridge is the silliest thing I've ever heard of. The improvement in speed accuracy over any decent belt drive table is undetectable by the human ear. I mean wow and flutter in this regard. There are people who can hear the slightest pitch differences. Fortunately I am not one of them.  
 

Regarding my pre-amp, MFA Lumi, situation, I hope it will not cause a distraction from the topic at hand. However, it is integral to the analog chain, and I could seriously use your help / opinion, so please bear with me. I have Lumi A1 or A2, with two transformers in the PSU as opposed to four in the B-2c series. In my correspondence with Scott Frankland, he regarded the B series as the 'most advanced'.

@vuckovic '...Lumi is still the world class preamp!...'
The high regard given to the Lumi, I believe, is primarily for its phono performance. With the La Platine / Trans- Fi / ZYX entry level cartridge combo, the soundstage bleeds right out of the sides of the ET LFT-8b's. The depth, layering, and 3 dimensionality ..etc are quite something, hence my push on the TT front to get more. Instinctively, I know the Lumi will not only keep step, but is driving the herd. 

While I only listen to cds' 20% of the time, the listening experience is very different. Not unpleasant, but everything is scaled down, the 'stage is restricted, resolution is down, and I am straining to hear the ambience of the venue...etc. The thinking was that the culprit lies with the vintage Wadia 16 until about a month ago. As the Lumi was sent for repairs, I decided to plug the Wadia directly into the Von Gaylords Nirvana mono's. With its own digital volume control, I was listening to a more resolved, more transparent, and slightly larger soundstage presentation. It seems clear that the Lumi line stage was the issue.

I wonder if your audio buddies or @lewm can confirm the disparity between the line and phono stages in the Lumi? If not, then I really need to get it fixed by Scott!!

@lewm What have you moved on to after the Lumi and why the regret?

For now, I am leaning towards using The Lumi strictly as a phono preamp through the Lightspeed Passive Attenuator. In other word, keep the goodness of Lumi and optimize elsewhere. This passive device is proving to be quite something and a subject for another post.  @lewm I think you are skeptical of this one. 

@junk981 What is the motor that you are using? 

@vuckovic and @junk981 In corresponding to Thom Mackris of Galibier Design, he advised to defeat the suspension of the La Platine in order to use the tape drive with his motor. Since you are both using tape drive, is there a problem with the tape staying on the pulley?

@mijostyn Thanks for your advice. I have moved onto a Trans- Fi Terminator Linear tracking arm from the SME V. As mentioned elsewhere, the LT arm is far superior.

I do not use original suspension - you can read my first post in this discussion. I am not surprised you got more transparent sound with Lightspeed attenuator - it just shows you potential of your system. Lumi has vintage sound - great dynamics, body and texture. On other side it lacks ultimate transparency, details, frequency extension and see- trough soundstage - those were the reasons I did not want to go that route. Finding something between is very challenging.... If you are happy with Lightspeed's dynamic and body in your system - you have winner combination...

@vuckovic
Would you mind sharing the dimensions for the 1/2 inch tape drive pulley for the stock motor spindle? I've got stacks of half inch audio tape in my home. Do you just pull off the standard brass V pulley and push the replacement delrin one onto the motor spindle?
Thanks
Charlie