Certainly works for me it's not new.
I've been machining on epoxy granite bases for over 10 years (Diamond Machining)- cuts down on vibrations.
Here's what my machine manufacturer says:
The machine base is constructed of an epoxy/granite composite. Epoxy/granite is made of 95% crushed granite particles mixed with an epoxy binder. It provides excellent thermal stability and vibration dampening characteristics, as well as allowing the incorporation of swarf extraction tubes and wireways into the molded structure.
The base is isolated from its fabricated steel frame by a passive, three point, pneumatic vibration isolation system.