Which comes first, the main hole or the dimples?
I can see an angled cut, if it overhangs enough, might produce a nice shear angle.
Of course the perpendicular is probably more than good 'nuff.

I've tried the single hole bashing method and as you mention in your blog, kinda rough.
This looks like a great way (simple) to get good results. I'll have to try it and see if case hardening can make for a really long lived tool!