On my iPhone4, I had a PowerSupport protector on the back, even though my phone was always in a case. It worked out nicely, because after 2 years of use, I took off the front and back protectors and my phone looked pristine. I'm passing it on to my sister-in-law and am pleased to have a really nice looking phone to give her. Right now, on the 5, i have a SPG on the front and nothing on the back (phone is in a Casemate case). What are your thoughts on a back protector for the phone under a case? What protectors are thin enough to do that?