Well, it would be silly to waste time and resources to find exceptions to the rule. Which, yes, IS the whole point. Theta is a well-built cable from a reputable brand that no doubt works well in other systems, but it's silly not to extrapolate information and learn from the experience. It IS a $1000 item, not a throwaway cheapie you can toss in the closet if you buy it and it doesn't work out. Theta makes a fine control for cables that use silver. In my case, I also own a Gamma PC (copper) and it had none of the brightness/over-fast transients of the Theta.
Thankfully, plenty of options with copper and even gold options. If you have a recommendation for a silver PC that isn't absurdly expensive and can "warm up" a cool system, please do so. Thanks.
And FWIW, I did ask about the Snake River Signature (which does use some silver), but it was unavailable for borrowing at CC. My experience with the Cottonmouth Gold has been very pleasant thus far, so no big loss there.