Have you tested how it works on very hard steels (60+HRc) or high grade stainless?

In my experience, these carbide gizmos are really handy for lower-end blades (kitchen knife or the like) if you pay attention to how much force you're applying and don't overdo it. But at least the ones I've tried had problems with really hard tool or stainless steels - the ones that tend to be a pain to sharpen even on a very good synthetic stone.

Anyway, looks like an interesting product. I use a pocket diamond card (600 grit) and a file on my Leatherman for field sharpening though and I'm pretty happy with the setup.