I had a pair of the Nano Reference ICs w/ Xhadow RCAs. They had some very appealing qualities- smooth, detailed, with great separation, and clear bass. In these areas they bested some very good cables. However- in my systems, they sounded a bit rolled off on top, which was not a good match. If I had brighness issues elsewhere in the chain, I may well have kept them.
I also had issues of picking up RF- I had a buzz when used in my main system. I used copper foil to shield them, which helped.
However, I've since moved to Grover Huffman ZX ICs, and they have bested everything else I've tried.
I'ma bit curious about the Cerious SCs, though.