Welcome on board, CapeCodVivarium.
I'm the person that bought a bucket of the new substrate and all I can tell you is that it appears to be the same material as Soilmaster Select/Turface Pro League. Specifically, a fracted, gray, Acryllite clay.
Here are the pictures I posted of the camparison between it and Turface Pro League...
The linked-to thread was locked (by me) because in the end it was no longer about the quality of the product, but rather focusing on the business practices of the vendor.
As for the material itself, I can tell you from personal experience that fracted Acryllite clay (regardless of who's selling it) is a great substrate save for the fact that it is very light weight so can be blown around easily by fish or water currents. It's weight also can make planting larger stem plants a challenge as the material often isn't heavy enough to hold them down unless done in a deep bed of it (3-4").
The material has a high CEC rating so is good for absorbing nutrients and keeping them available for the plant's roots. It has little or no Fe (as opposed to Laterite or Flourite).
Where the original thread got derailed was on the fact that you can obtain Soilmaster Select/Turface Pro League for far less at a Lesco distributor (for Soilmaster Select) or at a lawn and turf maintenance supplier (for Turface Pro League). Both are used in the maintenance of baseball fields as an infield ammendment so calling the local parks and recreation department may offer up a lead as to here it can be obtained in your area.
In any event, should you be unable to locate a local source for Soilmaster or Turface, you now have Aquariumplants.com as a convinient online source for the same material.
In actual use, you'll be best served by dusting the bottom of the tank with some finely ground peat moss, then adding a healthy amount of mulm, collected from an established tank, to the substrate...the same process used for any non-ADA-type substrate.