I just had the HC version on loan for my Spectral amp. I thought it gave a nice full sound, with three-dimensional body to instruments and low-end weight. These were factors I felt like I was lacking before, so I may have been focusing on them more - and not noticing other attributes, good or bad. I also don't have a real strong list of other cords for comparison.
From what I understand (not from personal experience), these are very close (say, 90%) in performance to the next model up (Python, I think) whereas the previous cord at this level of the Shunyata line-up was well below (Taipan, I think). Therefore, the Black Mamba might be a strong value.