FWIW, I know Jon and I've attended a few listening sessions with him. I think he's very good at describing what he hears because I've been there when we've heard it and he's described it. He's listened to a lot of gear in a lot of systems and has developed a knack for identifying how a certain component, wire, tweak, etc. impacts the sound of a system. I'd trust his judgement over most of the published reviewers I've read.
So if he says 4S11 is a dark, slow plodding cable, I believe he had good reason for saying that. I also know that he would be the first to qualify that as a judgement on his part and not a dogmatic fact.
That said, I have 4S11 in my system and would not describe it that way, probably because I've voiced my system to my liking with that cable in place. I've heard power cables, interconnects and speaker cables that dramatically change the sound of a system. Context, system voicing, and taste determine whether the change is better or worse. I'm a cable cheapskate and I'm quite happy with 4S11.
If you're in SoCal, invite Jon over sometime to hear 4S11 in your system. You might just change his mind. Or he might bring a few other cables over for comparison and he might change your mind. In the mean time, enjoy your cables and your music.
Russ