It's hard to imagine than 1200G is better than SP-10mkIII, maybe SP-10R is better or equal, but the 1200G is not Technics reference turntable in the production line, while the SP-10mkIII was the reference for such a long time.In practice the SL1200G is the most speed stable turntable in production right now. The initial release specs on the SP10R don't show a big difference between the two.
The SL1200G is a complete from-the-ground-up redesign and only shares its appearance with the older SL1200s. Its a very well-thought out design; is more speed stable and has considerably more damping and a very dead plinth. IMO they should have made it look different if just to avoid the obvious confusion people have thinking is nearly the same as its predecessors and look-alikes.