There is almost no current carried by interconnects. So the conductors can be very fine without causing losses. It is when Amperes of current are passed -- say in power cords or speaker cables -- that large-gauge conductors are needed.
My favorite XLR cables are those made to order with Neutrik gold XLR connectors and Mogami W2549 cable. You can have them made to order by a pro audio shop (I use ProAudioLA, who do a great job) or find them on Amazon, sold by a company doing business as World's Best Cables.
The above cables have very good shielding. If you need the best possible shielding because of interference, use Mogami W2534 instead.
The duplication of posts you asked about seems to be a technical issue at Audiogon.