Heavier can tear up feet, due to its coarseness, and lighter cannot be properly stretched to remove the wrinkling that can sometimes cause tripping and injury. Also the mat itself will wear at the same rate as the double lock seams so the additional cost of this double stitching offers no additional life or strength. Many feel vinyl is the best all-around choice for a mat cover. Vinyl is always easy to clean and maintain. Its cost is generally higher than canvas but if manufactured properly will last longer.
Seams can sometimes be a problem depending on the manufacturer or supplier.
To form its seam vinyl is overlapped and glued. With vinyl you have two surfaces to choose from on the same piece of material. The other side will be smoother or slicker. The up side is that it can be effectively and easily cleaned - even after every class. It is difficult to determine beforehand which side will be best for your dojo because you can't tell how the surface will truly perform until its actually down.