how is the back of the ip4 holding up against scratches? Cause I originally got 2 zagg shields for me and my girlfriends ip4's to go on the back and then bumper around the sides. I really like the bumper but the zagg sheilds are useless they keep peeling and getting bubbles. so I finally peeled mine off and im using a $1 ebay case currently. I want to go back to my bumper cause it feels like it would protect better if the phone was dropped but im afraid the back will get all scratched up. is the back as scratch resistant as the front?