I have migrated from Mass to Lightweight>Rigid and with Stabilised Properties on my Plinth Design in use.
I am in the process of taking this method up a notch, and will be upgrading a used material, to one that has properties that will be difficult to surpass with the selection of materials available at present.
I have no concerns for the Rega Approach, they have adopted a method that is infiltrating the field of Plinth Design, where a material iis selected that has very good damping properties and a highly efficient dissipation, when compared to material used as traditional choices.
Learning more of the Rega material selection would be an interest to me, I will settle down with a coffee at some time and look into the design intent.
I cannot see myself considering a Massey Plinth Design, as a Bespoke Build for any future endeavours. I am very familiar with Massey Plinths in both Stone, Wood and Metal, the owned Stone versions are now limited to one only, that is a Branded Manufacturer's Design, there are a couple of Lead/Timber Constructed Plinths knocking about. These are now not the desired Plinth that is seen to be the best mounting for a TT's Chassis or Mechanics.