I suggest ordering from a company that provides a return policy such as Signal Cable or Morrow Audio. Talk to them about which model is best for you. I like the Silver Resolution from Signal.
Is it true that mixing metals can produce different sonic results?
Never compared the sound of different connector metallurgy, but silver and copper are combined to make the conductor in my cables, (Purist Audio and Grover Huffman Empress).
I think it's a generalization to say that only copper or only silver will sound right in a given system. It depends on the design of the cable which includes the conductor, the dielectric, and the dampening material, and of course the design of the components being used.
The VPI to the Herron should be treated differently than line stage components where almost any IC can be used. TT to phonostage requires a low capacitance cable, plus this is where you are likely to hear a difference in sonics between different metals and cable design.