The Q cable I am using is similar to 4TC, in that it is a twisted configuration, but transcends it because it is a type 2 litz which means it is a "twist of a twist." Not only is it effective as shelf shielding, but it completely eliminates skin and proximity effect. It is evident by how nothing sounds rolled off. I testify to you that this is a world class cable. 4tc is not. This is a case where you really have to forget the reviews and magazine ads and try for yourself. If you research what works best with SET and low powered setups, it is frequently Litz or just look at what Tommy Horning puts in his amazing Horn Hybrid speakers silk cut Litz.
Just a thought, if I was to go with solid core, I would be much more apt to go w/ Zman's design over Speltz. Reason: he go's the extra mile with the Cryo treating and twisting it. Speltz is just a solid core wire nothing to it really.