Actually, rhodium has a much less conductivity than gold. However, I think that it's superior for analog circuits. Silver has the highest conductivity but, in my opinion, presents its problems. I did read once somewhere that silver does not have any natural dampening for electrical resonance - this may be why it is described as bright/harsh. As far as high frequency response, I think rhodium has a better and more extended high frequency response in the analog spectrum. Much better than gold (which is warm sounding and rolls off highs).
