I'm pretty carefully handling my TF, and the dock provides great protection for the screen when not in use, or in transit. It won't rub on the screen, and the Gorilla glass is pretty scratch resistant.
I wouldn't think of using a screen protector on it, and degrade its gorgeous display, especially after just returning from a transcontinental trip, and watching 5 HD rental movies on it during the travel. Beautiful. I love the TF more every day.