Trans-fi Audio rim drive motor vs VPI with SDS

I am considering using the Transfi Audio rim-drive (TFARD)motor and speed controller over my 600 rpm motor and SDS. My concern is the speed control/voltage regulator: the SDS makes its own constant and stable voltage. This eliminates speed variation.

Does the TFARD perform the same function or do I need to acquire a voltage regulator?

Thank you for any help?
I purchased the Teres Verus direct drive for my VPI TNT. I have not experienced the shifting pitch that Doug Deacon experienced. Mine is the newer speed controller with the smaller incremental dip switches. As recommended from one of Doug's other threads, I used a downloaded strobe image and taped it to my platter (11.5" 17lbs) and used a CFL. I held a pointed object on the lines as a reference to set the speed.

The sound is distinct and sharp. Notes have a well defined start and stop. Bass is well pronounced. Low level music and music-hall resonance is evident. Maybe others aware of this: Most all recordings come from a tape source and there is a bleeding of sound that prefaces the striking of the recorded note. I could never hear this with a belt or thread drive. Yet, with the Teres it is very apparent (It is not the highlight of listening to music. But I point it out to illustrate the depth of music that is extracted with the rim drive.)

I listen primarily to classical music and big band. I find it very satisfying. It is a bit costly. However, when compared to SDS and a VPI motor, it is fairly comparable.
Why not the VPI rim drive?
I didn't have an opportunity to audition the VPI rim drive. I had to rely on the credibility of JohnC's review, and he gave the edge to the Teres Verus. It also seemed intuitive: There are still belts that indirectly drive the platter -motor to idler wheel and idler wheel to VPI platter. That leaves more room for compliance when compared to the Teres.

The whole concept of rim drive/idler drive is to eliminate elasticity in the drive. The only part of the Teres that has elasticity is the square rubber ring around the drive wheel. Physically, there is negligible space for compression of the wall of the rubber o-ring.

And my listening experience has been very convincing: I enjoy the Teres.