I thought I didn't need a screen protector on my first M8, that was until I dropped it from around 2/3 feet and got a lovely single crack from left to right on the screen. Since that I've gone back to using Spigen Glass screen protectors.
screen protectors protect against scratches - not impact. better off with some sort of case if you're worried about dropping it


Especially if you're going to use a case on the thing...the darker colour always looks a lot better in my opinion.