Man, this thread has really taken off!
Tbg, from their website it's evident that the Wolff ICs uses carbon and silver. Presumably they don't use a pure carbon shield/return (for low shield resistance) and and therefore can get away with longer lengths.
I concur with your observations of the van den Hul First, which is particularly sensitive to ground current hum due to its high shield resistance (4.8 ohm per meter), especially if you have a "dirty" component with excessive voltage present in its chassis. However, when it works in your system, IMHO this cable can sound magical. In my experience, the vdH Second (which has carbon signal conductors and a metal shield) is quite unfussy about equipment matching or long cable runs. For these reasons I prefer it to the First.
To Herman and Sean, FWIW I don't see why you guys should leave this thread in frustration. You have both made valid and constructive points. I don't think anybody questions whether carbon is a poor conductor -- it is when compared to the metals commonly used, like copper or silver. However, I think the real question is whether resistance is of overriding importance in all applications. When it comes to ICs, since we are dealing with very low current, my opinion is that resistance doesn't matter that much. If your amplifier has an input impedance of 20K ohm, then to your preamp it will "look" like it's driving a 20K ohm resister. Given this situation, what difference will the extra few ohms of resistance in the interconnecting wire make? As Herman has noted, it is negligible. Other wire parameters can be of greater importance given your particular application, but rather than go on, I will cite a reference that tells the story much better than I can:
http://www.tnt-audio.com/clinica/intere.html