Just keep in mind there is a reason why scratches occur (it's primarily due to rubbing, and it can be from either crud getting between the case and phone, or from the case itself).
While the Incase IS harder, the flexibility of the Tones causes it to move more back and forth over the edge of the phone. Again, it's NOT bad, but if you are one of the super OCD folks (for example, do you believe in "scuffgate"?), then the "rub" marks the Tones case leaves on the edges of the black iP5 might bother you.
Not sure if it happens on the white (I've only seen 3 slates), but on those 3 at least it most definitely DOES "damage" the chamfer edge, even if it's just a little bit.
If you kept the case clean I bet the Incase wouldn't do that, because it doesn't flex nearly as much. If crap got inbetween sure, but the case itself probably isn't the source, as it appears to be with the Tones.
No biggie, and my wife is still using her dirty Tones anyway haha...