Yes, it's all supposition at present.

I did look at some scrap blocks today and it seems anything around what appears to be from a 0.2 to 0.4mm radius is a 'sharp' corner for this stuff so a flat tipped v-bit with a 0.1 or 0.2 tip might work, might even be worth trying some of the 3mm engraving cutters i was gifted on it.