Do you mean the ones with a slightly raised cup, and an automatic ball return?

If so, I wouldn't bother. When they are packaged they are rolled up / folded really tight, to the point where the surface stays 'bumpy' indefinitely. Also, the outline of the mat provides alignment assistence that you won't have on the greens, which makes it waaaay to easy to get a streak going. I'd just stick with putting on the carpet.