The scratching on the band happens with some cases too. My 4 ended up with lots of scratches/polished bits around the corners, and that was in a case (good quality/brand, plastic back, rubberised surround, forget the name but most of them are similar). What causes it: you get tiny bits of 'stuff' from your pocket or wherever, and they get inside the case. Then the case moves just very slightly against the phone, and it basically rubs the tiny little bits of stuff into the metal band, polishing or scratching it. It happens slow, but it does happen.
To avoid that this time round, I'm thinking there's 2 options:
1. A band, but regularly take it off and wash the crap out.
2. A case that has some kind of felt material inside. I found my iPhone 4 case trapped a little dust at the back, which scratched the glass on the back of the phone. After that I cut some thin screen-polishing cloth to shape and fitted that into the case, which stopped it scratching completely.
Anyone know a case with some kind of soft fabric type material (NOT silicon or any kind of rubber) inside? Otherwise I'll go for the bumper.