Jason, I don't grind them, just set one cutting edge to centre height and they cut a treat. For holes from 1mm to 6mm, I only use these.
I thought about snapping with a hammer but was worried about how it splintered.
I have some diamond files, I suppose I could use them to nick the shank.
Diamond slitting saws sound interesting. I will have a look at those.
Cheers
Steve