silver is the best conductor not gold. copper after that. on that note i wonder why not silver plated conectors?
gold is purely cosmetic but may be better than the chrome plating on most cables(on a basis of conductivity) and corrodes less than copper.
honestly no audible and probably no measurable diference. there are many location for interference to enter the guitar, if it's sheilded well and no loose grounds you'll have no problems.
if it's not sheilded well then all the gold parts in the world wont help you.