In my research for designing a plinth for my SP-10 Mk 2, I've read about and talked with Albert, and read the L-07D site. I agree that installing some form of RFI shield should be beneficial.
As Lohanimal points out DD motors are directly below the spindle, therefore will be close to the cartridge for at least the inner half of the LP during play. Belt drive tables locate their motors in a variety of positions, depending on brand and model. They may or may not be in close proximity to the cartridge during play. I believe this is why some folks experience the dreaded "Grado hum" while others have no problem with the same model cartridge.
Years ago I read an article on shielding the tt motor when hum was a problem with cartridges like the Grado. I think Albert has a much easier solution - fit a sheet of material designed to shield RFI to the top of the platter (under your mat if you use one) and this should protect the cartridge through it's entire arc of play.
Lew, I can't promise but I would expect the weight of a mat/record and possible use of a clamp would eliminate any new problems from vibration.
And Lohanimal, for the record (so to speak) Albert designed his plinth (including shield) for a SP-10 Mk 2. Recently he bought a Mk 3 and I assume he will use the same or similar set up with it.