I agree with your opinion on the Ark stone Arron. Although they are still hit and miss in my hand. I still think, at times, that I can feel a difference in the edges from a 12K and a 20K but its really hard to say for sure. I think anything past the keenness of a 12K is next to impossible to feel. But the comfort levels do change. Thinking this is to do with less stria left on the bevel at the edge. And this can be done with a well-burnished Ark. In my opinion, Burnishing makes the biggest difference.
JMO