I feel that on really hard Jnats the stones do benefit from that finer smooth finish. On the ones that aren't that hard you can remove the lighter scratches with nagura from the stone so it is resurfacing itself and fixing those before the blade hits them. On the harder stones not so much. Plus on the harder stones those sharper edges from scratches even the ones you can't see are not giving like a softer stone on that edge. I know there is alot more going on here with the surface friability and hardness too. The nagura with also make a difference of course.

I have to agree from my experience.