Yes, silver is a better conductor, no doubt about that. About 4% better. Does it matter for most things? I doubt it. But marketing hype by cable salesman will directly contradict my opinion.
A 24/96 SPDIF signal is about 5 megabits/second, which is about the same bitrate as a home Internet cable modem (give or take some amount), and they aren't afraid to use ratty old copper going into the cable modems. That's pretty low tech really. On the other hand, digital cable probably has phenomenal bitrates, so that's a different story. Also, if they drop bits, and some guy sees a glitch on his new 99" high def TV, then they have a pissed off customer and have to send a high paid tech out on a call. In that sense, spending a few extra bucks on cable, even if it might only reduce the likelihood of problems a little bit, is good business sense.
If you have a run of copper in your house now, and you aren't hearing glitches, you won't hear LESS glitches by switching to silver. And you won't hear higher highs and lower lows.
If you just want to run it, run it.