Obviously silver reflects more than gold. That's just...basic physics. Silver is colorless, therefore absorbs no specific spectrum. 2nd graders know this.
The thing is, this would only be applicable if the laser were using white light. What matters for a CD and any other optical medium is how well it reflects a single color, not all colors.
Wikipedia says that CD player laser wavelengths are 780nm. Since the spectrum visible to humans ends at about 750nm, it's pretty much impossible for us to judge how easy it is for CD lasers to read a given type of disc based on how we perceive its color alone. This probably has something to do with why those black Playstation discs work.
EDIT: Looking into this a little bit more, I found this chart:
Pretty interesting. Silver is more reflective as a whole in the general visible spectrum, but gold is slightly more reflective in the red and infrared spectrum.
Apparently, DVD players use 650nm lasers, and blu-ray players use 405nm. Therefore, a blu-ray player would have an easier time reading a silver disc, while DVD and CD players have a slightly easier time reading gold. Perhaps the reason why the MAM-A representative told vacantplanets that silver is better is because it's a good catch-all.
Of course, we're only talking about pure elements here. Who knows what happens when you start getting into all the different chemical compounds out there?
Meanwhile, it's ironic that aluminum doesn't look very good on that chart. I suppose that the reason why pressed aluminum discs read better is because of better contrast between pits and better uniformity in the way the pits are strewn about the disc.
