Re: Zebra mats over carpet?
Is your question regarding the softness of the mat on carpet vs. concrete?
Zebra mats are durable and great for rolling with or without carpet or padding or anything.
I've been in dojos with zebra-like mats laid on concrete and they were fine. My dojo has padding laid out over concrete with a tarp cover and it is sufficent.
My advice would be: take whatever floor you have and use it. Make sure that it is cleaned throughly and has a good surface with nothing penetrating through (carpet tacks?) and just go for it. Carpet, Vinal, Concrete... I wouldn't worry too much.