I formerly used Alpha Goertz big shiny copper ribbon MI-3 for excellent full range results, including body, detail, and transparency. Then added for the upper treble range, silver ribbon AG-1, with bi-wiring. Similar to your speaker cable search. By using cables from the same company, I did not feel any problem with integration of different parts of the audio spectrum, and there was an overall perfecting of the sound. I cannot tell whether WAF allows for ribbon cables.
My current cables are Gregg Straley's custom single wire cables, which are the best to my ears, very low cost, and come with money back guarantee. They are coated with an attractive finish in the red spectrum, so cannot know whether they appeal to the fashion police, in your household. Omega Mikro are out of my league price-wise, and are probably more exotic than you really need to achieve satisfying sound.
I found all the attributes you mention, by switching to a single cable, so the copper-silver debate is not the sole factor in achieving system synergy. Nor is going exotic, with its more demanding set up constraints in a room shared with rest of the family.
