I'm torn on the screen protector issue.
I did not have one of my 8X, and over the course of 2 years, the Gorilla Glass 2 kept it scratch free. Not a mark on it. I assume GG3 is even tougher (actually was about to go online and read up on it) so I'm probably NOT going to put anything on my Icon. I should note, I am very careful about where I put the phone, and what I put it near. I never put it in a pocket with anything else that might scratch it (keys, coins, etc.) even though I've seen Gorilla Glass 1 marketing showing people unable to scratch the screen with keys and razor blades.
If I was going to do something, I'd go Zagg. They are a PITA to get on, but once on, the new HD protectors (especially when your device is on) are undetectable. That's what I have on my Surface 2.
Only thing that concerned me, if I were going to go the protector route, was how well they stay on the Icon's curved screen. I would not think a flat screen protector would lay flat at the corners.