While looking for another tool rest in the approx. 8" size I thought about trying out one the Robust rests. All of the ones I have now are made out of softer ductile or cast iron. The advantage of the Robust rests seems to be the hardened top bar that resists dents and scratches. All well and good but what to do if the bar becomes marred. A ductile iron rest can be filed and smoothed down, hard to do with a hardened rest unless ground. Am I missing something in my reasoning? I would like to try a Robust rest but don't quite see the advantage.