I am convinced the "self-healing" designation on cutting mats created after Olfa (the original) had been on the market a while, merely means that the mat doesn't cut through like, maybe, cardboard would. In my quilting/teaching experience (34+ years) none of the other brands are made of the same substance Olfa is, and all of them seem to dull your cutting blade faster than the Olfa mat does. When I am paying $3 and up for blades, I do not want to worry that my mat is making the replacement more necessary; I would rather pay more up front for quality, than pay a little less more often for replacements. I have had Olfa mats for years and years and can still use them. I store my unused ones, or those going away from home to sewing events, like this graphic below and never have warping problems.
Jan in VA