I just use the fine rods on my Sharpmaker. I have a Spyderco Tenacious that I recently did an edge retention test on it. At the beginning of the test I could push cut through a receipt. I then made 15 various kinds of cuts on a Monster energy drink can. At the end I could still cut through the receipt in very fine slices but not push cut as well. I think the Flat grind on the Tenacious results in a slighty toothy edge because if I run my finger nail on the bevel about the edge of the knife I can feel small ridges on it.