I'd like to know more about Fibrament Baking Stones too, but their web site prompts at least as many questions as it answers. For example:

Q: What is the composition of FibraMent?

A: FibraMent is made from a proprietary blend of heat resistant and conductive raw materials approved by NSF International for use in baking ovens. (If you really need to know the ingredients you have to buy the company.)

Are they really worried that someone will set up shop in competition with them, or are they worried that people might not buy if they knew what the stone was made of?

Q: When I baked my last Pizza some sauce and cheese spilled onto the stone. How should I clean it?

A: Take a dry rag and wipe off as much of the residue as you can. Use a rubber spatula to remove any stubborn spills. Be careful not to damage the surface of the stone.

It sounds like the surface is pretty fragile. I regularly scrape the surface of our baking stone from King Arthur Flour with a stiff putty knife and there is no sign of damage.

I have a large stone from King Arthur that sits in my oven, gets stained and I wonder why it is even there. When I take it out, I don't see any difference in the cooking.