Just having got an M8, I took a similar route which I took with my Canon. I bought the Belkin "generic" screen protection film, like they make for iPhones etc..
This version comes in large square sized with grid measurements on the back to make cutting to size easy.
Then you just apply the fine film to the screen. If you've never aplied this ultra-fine film before, you will probably waste one on the 6 sheets in the pack "learning how to apply it eaxatly - it takes a lot of care and patience.
The end result is that the only appearance change is that the screen looks a bit more glass like. It only enhances the image apearing on the screen and certainly has no adverse effect on the screen's clarity.
The nice thing too is that when it ever shows any sign of wear, you simply peel it off! It adds no bulk to the camera screen as the film must be less than 1mm think!
A simple and effective option and you can do 12 applications from the 6 pack - all for about AU$19.00 (or even AU$15.00 if you push for a discount) - so it's cheap too.
I have the same stuff on my iPhone and my Canon and it certainly protectes the screen perfectly.