In my experience, the anodized black finish on Leica lenses holds up better than the paint on C/V lenses. I always thought of this as part of the value-engineering that lets C/V and Zeiss bring you excellent lenses at a lower cost. It never bothered me, but my black C/V and Zeiss lenses have been worn to the brass on knurled or textured focusing rings within a few months of purchase. My 1980's black 50 Summicron, by contrast, has shown little wear, despite the use I have made of it over the last 15 years. Hey -- it's all good with me. I care only about the glass, and I have really enjoyed my C/V lenses, right back to the first one I purchased.
Ben Marks