Gold is nearly useless for post-SHTF purposes. Its too valuable. Last i checked gold was around $1600 an ounce, what are you gonna buy with that? Even the 1/10th oz. gold eagles are worth $160 still a large denomination. Silver is much better in this aspect. Gold is excellent for pre-SHTF wealth preservation.
I personally believe for precious metals, that Silver Eagles and pre-65 90% silver quarters and dimes are best for purchasing things post-SHTF.
While precious metals are good to invest in, i believe even more valuable at least immediately after an event would be trade goods.
Alcohol, tobacco, chocolate, toilet paper, canned food, bottles water, flashlights, batteries, common types of ammo, pocket knives, common durable clothes, etc. will be in high demand. I believe it would be easier to trade something immediately useful than some silver.
And no one really knows how it would really play as we as a country havent experienced anything like this yet