drop tested Incipio Feather!
well yesterday at work I field tested drop durability of our 3GS in the Feather. I have the same case as the OP... If this mishap had happened with my Power Support Air Jacket it would have been a completely different outcome, because of the material type and wrap around of the air jacket.
my phone was at ear level, almost 6 feet, it slipped out of my hand as I swung my head and it launched my phone straight down hitting the concrete directly on the top corner of the phone/case. Surprisingly enough, i didnt drop the call, the phone is intact and the case suffered only large gouges. When it hit the ground it flipped onto its back so i was thankful the screen didnt go sliding across the concrete slab. The phone was perpendicular to the concrete when it hit the corner, the corner took the full force of the drop.
If it had been the air jacket i think the case would have shattered and it would have almost certinly caused more damage to the top of the phone and the bezel since the air jacket leaves that part of the phone open.
when i took the feather off my phone to check it, i did notice that over the past 2 weeks or so there has been some rubbing of the feather onto the side bezels of the phone. nothing too significant.