I held my breath when I dropped my original iPhone. I was standing in a blacktopped driveway, the device was in one of those reasonably protective Incase soft cases around back and sides, and the thing fell about 30 inches. No harm done but I had one of those slo-mo event experiences, where three-quarters of a second or whatever it was seemed like five long minutes.
I've kinda coddled the 4S in its bumper (and keep it jacketed in a Waterfield suede sleeve in my handbag) but no problem even after all this time, so not going to start worrying over it now.
Not concerned about the 5C (in an Apple case) even if the glass is raised off the surface of a table just a tiny bit when placed face-down on the front rim of the external case. If I haven't busted the 4S yet making that kind of set-down, don't think I'm going there with the 5C either. But, I might look into a Waterfield jacket for the 5C too, if they will be making one that accommodates the device in Apple case. I like the jacket that has a black stretchy-mesh pocket in front for earpods (and money or a credit card if I'm just out and about on foot).