Re: Zebra mats over carpet?
When moving any tatami or modern sport tatami substitute you have to be very careful about the way you carry it, etc. It should always be moved perpindicular to the floor instead of flat. Zebra mats are constructed with the covering glued to the foam. If carried or stacked wrong the covering can be broken away from the foam which causes the bubbles. They should be flat and not bent. Traditional tatami should be handled in the same way.
I can't imagine how much I would dislike working on sport tatami on top of jigsaw foam mats... Ughh! (as I saw described on another site) Excessively soft mats create many problems for budo practice. I was on a very soft foam mat with a canvas cover for a weekend in Houston recently and my knees and lower back are still talking back to me. My advice is the firmer the better as long as it absorbs shock appropriately.