The SSX upgrade on Skutt wheels is highly recommended. It makes the wheels quieter. It makes the pedal smooth and responsive. It maximizes the torque and power of the motors.
Skutt Kilns took over the Thomas Stuart Pottery wheels several years ago and continues to build them with same incredible standards set by Thomas Stuart.
This drive provides incredible sensitivity for the foot pedal at very low speeds. If you are throwing wide, or tall, any slight variation in the speed of the wheel head can be devastating. The extra large capacitor on this controller has the ability to store more energy so it can transition between speeds with more precision. This is the premier controller. It runs smoother and quieter. There really is no downside.