Eastwood CONTOUR SCT® - Surface Conditioning Tool

I just used a grinder and the 3M Strip N Clean XT discs. They are $20 ea up here....probably $12 down south. I think I ran through 1 disc per panel on average. Its dusty but doesn't profile the metal so you need to run a DA over it afterwards. The question with the contour tools is how much do the drums cost and how long do they last? Can you get into all of the areas or is it just good for flatter surfaces?