Silhouette 60° Blades

I found out the 60° blades aren't always better:

I was cutting copper tape, which is about 1/2" wide. In each of the 2 pictures above, the top tape was cut by my 60° blade, and the bottom with the official Silhouette blade (45°). You can see that the top designs are starting to peel, while the bottom ones are perfect. I thought the finer blade would be better at details. Also - surprisingly, the 60° blade required a higher force to cut.

I suspect the protrusion of the blade was too much, because the backing was cut as well. This might have required a higher force and deeper penetration of the blade, resulting in a long portion of the blade being used to cut. Other theory: maybe this blade holder doesn't rotate as freely.