Morgan, I use KE-6(8) and KE-4 in my system. When I was using a 2-way speaker, I biwired with that, using KE-4 on the treble. Compared with other good-but-not-current speakercables I had to audition, I found both of these to be much-smoother sounding than the others, including AQ mixed-copper-and-silver stuff from the prior generation. NEVER did I find any silver-conductor cable to be bright sounding--in fact, it was the quality of the KE-4's treble that caused me to buy it. I now use it in parallel with the KE-6(8) driving my Quad 989s.
If one is driving a low-impedance and/or insensitive speaker, probably KE-6(8) is a better choice, as its net AWG of 12.1 will carry more current easily and better maintain bass-damping factor compared with KE-4's 14.5g, but other than that, it's great.
Where are you? (I'm in AZ.) I might have some pieces you could listen to.