You would likely loose the even lighting. The screen protector serves two purposes - 1. to protect the screen and 2. to distribute the light from the leds evenly across the screen. One of the Gizmodo editors dropped something on his NTG and the spot where it hit now has a bright area where the light is "leaking".
http://gizmodo.com/5907053/you-reall...ouch/gallery/1