Silver tends to be on the brighter side. I've found it to make the sound staging more spacious, sometimes thinning out vocals and taking them along with the mids slightly further back. Copper tends to add warmth to the sound, is less detailed than silver but has a more organic sound to it. Depending on the gear I could prefer either.
I've found this to be my experience as well, but keep in mind we're talking changes of 1-2% here, tops. I really liked what I heard from the Toxic Cables Silver Poison but the Magnus beats it (thoroughly, no contest really) when it comes to ergonomics.
I keep pestering The Wizard to make an all-silver Magnus cable...
Edit: At the risk of catching hell from half of head-fi, I really don't think the cost of the Silver Poison (we're talking a $300 cable here) is justified by the small improvements gained.
Edit 2: Given the fact that I am right now listening to ambient/chill house (Mike Sheridan) from the DX100 via a Magnus IC to the Rendition 1 amp via a Magnus cable to my 8.A, my point about value for money and The Law Of Diminishing Returns might be considered null and void.
Edited by Sorensiim - 5/8/13 at 12:06am