I've been using an exacto knife for greater precision. It's improved my scores a bit and so far the screen is holding up fine, though I have accidentally cut myself a few times. I'd say the blood is a bigger problem than the scratches. YMMV..
Mine is fine, but I've been taking excessive care of it. Had trouble with a few of the feel the magic mini games because I didn't want to press too hard on the screen. :lol