@slaw, I too would have to be considered old school (as well as somewhat old ;-), and our definitions of plinth are the same (see my post above): it is the "body" of the turntable (in a suspended sub-chassis table like the VPI HW-19, the Linn Sondek, the Oracles, AR’s, etc., the floating sub-chassis) that the platter’s bearing and (usually) the tonearm are mounted onto that I call the plinth. On a non-suspended table (the VPI Aries, the Regas), the plinth is usually one solid piece of either most often either MDF or acrylic, again onto which the platter bearing and arm are mounted.
On the Rock Elite, the motor is also mounted directly onto the plinth, same as the Regas. Whereas the Rega plinths are just a slab of MDF, the Elite’s is a shallow upside-down metal pan filled with damping pads and Plaster-of-Paris---very inert (non-resonant) and high mass. The motor height is not adjustable, nor does it need to be; both it’s and the sub-platter’s (the metal part that is attached to the bearing spindle, and upon which sits the 12" platter) height have been engineered so as to situate the belt in the center of the sub-platter, no adjustment necessary.
@nsp, the loading of the Londons (and older Deccas) is a matter of some opinion. The instruction manuals of some models recommend 47k, others 22k. The older Deccas were much more variable than are the current Londons, so no one figure was universal. Harvey Rosenberg (of New York Audio Labs fame, known for his love and knowledge of Deccas) told me he preferred 10k with his Deccas (this was back in the 1980’s). Zesto Audio provides a 15k setting on the MM input of their phono stage, specifically for Decca/Londons. The loading resistors in any phono stage can be easily changed by a technician; it takes only a few minutes. If you want to give a London a try, I recommend getting one with the optional Decapod mount; it provides a much firmer mechanical mating to the tonearm, and makes the cartridge body less resonant, less microphonic. The London Super Gold retails for around $1500, and may be the one to try first. The Reference is around $5300, a lot of $ to take a gamble on!