Yesterday I had the opportunity to test one of Doug Thompson's new 15V 5/8 bowl gouges. I started and finished an ash bowl with the tool straight from the package, I could have taken the finish cut inside without sharpening but I wanted to see how it sharpened. Using the white wheels on a slow speed Woodcraft grinder I had no trouble putting a new edge on it. It definitely is harder than the 10V but I was still able to use the white stone. If your looking for more cutting time between sharpening you might want to try this one.
Bill
Bill