well it's hard to argue that capacitance doesn't effect tone. Because it does lol. You lose high end over distance it's a fact. More capacitance less high end content.
And you can hear the capacitance comparison here:
http://www.aqdi.com/faceoff.htm
In this cable tone comparison, it's pretty obvious.
Also, some great charts showing different pickups through different cables and what the resulting effected frequency range is.
http://www.aqdi.com/cgi-bin/database.cgi
Just because you can't tell the difference between Coke and Pepsi doesn't mean there isn't a difference. But to say that the least capacitance cable will sound the "best" is a subjective matter. Perfection doesn't mean pleasing lol. Like the imperfect frequency response of guitar speakers sound great with guitars. Then you try some full range speakers in their place and blam you hear all the frequencies you
don't want, but it's a more accurate representation of the tone, it just sounds awful. It's finding the cable that suits your tone needs and enhances your sound.