I used a big mat from JoAnns for about 15 years with no problems. Bought a Martelli at the Knoxville Quilt Show last summer, and what an improvement. Much easier to cut on and the lavender and yellow show up the fabric. Hubby is still using the big one from Joanns in his workshop.
Have the Olfas and notice the gouges don't heal too well; the same with the June Taylor. Love my Martelli.