Heres my thoughts, tearing makes sure you get on grain fabric correct yardage. Personally I have lost as much as 3 to 4 inches on a cut that was cut down a "cutting line" as if the grain was straight. As far as the torn edges, it doesnt really matter so much if you plan to pre wash the fabric. Most places I go don't tear, but I wouldnt mind if they did. :-D