The only reason for returning the matt was because it walked on my carpet. Although the carpet is not that plush it is dense and possibly has a high nylon content. I'm told that is why sometimes matts walk and sometimes they don't.
My computer desk chair with 5 wide rollers started to sink into the mat with only a few days of use. I can see this failing in a mater of months. The mat material used is not suited to this type of use. By the way I am not overweight.