Funny, my E62 lived in my pocket for a long time without a case and never got scratched up. It got scratched up after I bought a case and a mount to put it on my bike, and then it fell off the mount, out of the case, and bounced end over end a few times at 20mph. That scratched it up. The Krusell Cabriolet is not a good case. I should have bought a Classic like I had for my E61.
Perhaps it was so durable because the bottom corners are metal.
Obviously a good screen protector is required, as the screen will get scratched if you don't have one. (I used the shipping protector until very recently, when I was ordering a Martin Fields for my N810 and bought one for my E62, I had one on my E61 before I left it.)