How good is the Obsidian plinth of Technics SP10 ?

Recently I heard an SP10 MK2 playing music at a friend's place. It was mounted on the stock Obsidian plinth. It actually sounded very good. I wonder how good is the Obsidian plinth compared to:

1. Typical after market birch ply plinths ?

2. Custom designed plinth like the Panzerholz plinths made by Albert Porter ?

Any ideas ?
Chakster; what is the total weight. Cant remember..
Anyway ,there is different versions , one of the manage 10 kg each.
I'm a believer in Stillpoints in some applications, but in the case of an SP-10 Mk IIa in the obsidian plinth, three pairs of good ears had difficulty detecting any meaningful difference between stock footers and Ultra SS.  This may have been because the plinth was sited on a substantial 4" maple base. Much more improvement was heard with a 4mm copper mat on top of the stock alum platter.
Hi dgarretson.

  agree in the overall improvement factor, my micro seiki cu-180 had a bigger improvement on my SP10mk3 than the Stillpoints.   
    However, the Technics sitting on a 4" piece of maple may not be doing the stk feet or Stillpoints any favours.