@pindac , interesting. I have not analyzed that from a mechanical perspective. Both metals are very ductile and malleable. Wires of similar gauge will be just as flexible. Both will strain harden but not to a degree that would cause failure in this application. Both would break just as easily. I would think strength and flexibility would depend more on the material used for insulation. As an example Etymotic ear phones have Kevlar strands in the insulation. You can hang yourself with them before they will break. I managed to do it anyway, a long story. Silver is a slightly better conductor but in reality this means very little. Both will tarnish.
In Short, the best tonearm wire should be strong and very flexible. This depends more on gauge and the mechanical properties of the insulation. The highest gauge you can get away with maintaining reasonable strength is the way to go. As for which conductor to use? I would be willing to bet $1000 that if I did blind AB testing on a group of audiophiles none of them would be reliably able to identify the conductor. It is a shame that a group of us do not get together to perform tests like these. They do not get done because the media does not want to piss of 90% of it's advertisers and a wealthy audiophile has not come along to underwrite a group such as this.
As if it means anything, I had a choice of wire with Schroder tonearm. I chose copper. I thought the silver was a waste of money.
@bpoletti , if any of us can hear a 3mB difference in volume I am a monkey's uncle. There is absolutely no frequency response change between silver and copper wire in the audio band. So, I am going to have to agree with lewm on this one.