No experience of the Longdog but I had a conversation with John Burns at Pear Audio (UK distributor) regarding the upgraded WT power supply and his advice was to stick with the standard one on my Versalex?
Nick's a solid designer and makes a lot of PSU's under his own brand and for MCRU.
That said. Adding a stiff regulated psu to a bare turntable motor really doesn't bring much to the party. The UK mains is stiff and generally very tight on frequency and that's what drives an AC motor. I'd hold out for a PSU that creates a new, adjustable frequency to drive the motor and offers speed adjustment and some form of speed correction via feedback. That'll be a step-up in performance.