I'm even more worried about the exposed L/R buttons. I have an otherwise perfectly functional Nintendo DS with these buttons being unreliable at best (received second hand already like that). Not that I have any better idea how to solve this, but I'd definitely not just chuck it into a backpack. Maybe a pocket.
I'd prefer no scratches at all, even if that means sacrificing probability, I mean, we could always use screen protectors for that matter, in fact I did, but it never stopped me from overprotecting my clamshell handhelds.