To your first question, would you rather replace a cheap screen protector that broke or became scratched up, or the entire display for the same reasons? Screen protectors are sacrificial in nature so that damage isn't caused to the phone itself in most cases.
To the second question, I think I'm going to sit this round out. I used to use tempered glass protectors, but not this time. On my G4, it was replaced under warranty and I simply never got around to replacing the screen protector. Almost a year later and it's still flawless. My Verizon V20 has a clear plastic protector for shipping protection, which I'll keep on as long as it stays. When it can no longer hold up, I'll go without.
hi, thank you. And I am thinking about trying some new ones. I got a screen protector which is made of tempered supramolecule, which is flexible and wont crack. Have you heard about this?