Im thinking of getting a matte screen protector for my MBA. My questions are: 1. Will it screw up the keyboard (ie. keyboard imprint due to thickness of the screen protector, etc?) Note: I don't use a keyboard protection sheet 2. Will it affect the brightness significantly? Right now im doing 3-4 bars above zero, which i find just enough. 3. Is the matte finish worth it? Thansk!