The CH cable without the heat shrink is springy and the heat shrink reduces the springiness of the cable, adding to the ergonomics. Stiffness is slightly higher but in use it is better for me because it will stay more where you put it.
As far as a cable hardening, sweat and body fluids will, over time, alter the composition of many cables. There have been many reported cases of companies such as Shure and Klipsch having issues with their cables hardening, and these cables may do so depending on the material. Teflon, for example, should be immune, but PVC and other materials will not be. I am not sure the material of the CH cable so I can't say for sure. My SM3 cable is starting to harden...
The nylon or cloth over braid that the Lune and Arete use will absorb whatever comes in contact with them. Sweat, lotions on your hands, spilled beverages, etc. and all these things will, in my experience with this type of cable, add to the stiffness. Getting sweat on any cable day ofter day can be detrimental. The cable that has held up for me is the stock silver type of cable, which discolors, but there are no other issues I know of.
As far as the sound, the CH cable performs sonically better with the JH16 than either Null Audio cable and will add more to the 3D space as well as improve the other sonics characteristics.