Spyderco's theory is that the crisp perimeter on the Spyderhole makes opening more reliable. I find that to be true in the case of models with 11mm and smaller Spyderholes, and leave those as they came. However, for models with larger Spyderholes I really don't find the extra traction necessary and sometimes chamfer the perimeter slightly with sandpaper if my thumb tells me it's "too crisp". Still, I'm ok with Spyderco leaving them crisp, as it's far easier for me to remove a bit of metal to chamfer the perimeter of the Spyderhole than for someone who wanted more thumb traction to enlarge it to eliminate a factory chamfer.