I cracked my Zagg on the side with the edge of a seat belt and a fleck from the edge later (minutes) caused a very tiny scratch to the actual glass so yeah I'd replace it before anything like that happens.
I quit with the 3D edge. It was too much hassle with my tight fitting cases. Now I’m using the ThanoTech protector with my aluminum and TPU bumper and couldn’t be happier. And still no edges.