Words like "right" and "wrong" overstate the issue. Like everything else in a system, cables should be selected to give the proper balance, and sometimes a particular silver cable gives the best balance, and sometimes a particular copper cable does. I said "particular" cable because not all silver cables sound a certain way and not all copper cables sound a particular way. The material used is just one of the variables affecting the sound of a cable. For example, the Ocellia Silver Reference interconnect doesn't sound anything like how many audiophiles think silver sounds. The Ocellia is warm to the point of excess, and it has soft, rolled off highs. There is nothing cool, lean or bright about the Ocellia.
Back to the EMIA autoformer. I respect the views of those who have compared copper and silver versions of Slagle's SUTs or autoformers and selected the silver as better sounding. As I said earlier, I have only compared his SUTs and I found the copper versions to sound better in my system and for my tastes. The silver SUTs were a bit more detailed and certainly faster and more impressive on first listen, but in my system I preferred the more balanced sound of the copper SUTs.