They charge more for them, but if you were to go to sell a 10 year old Somali elephant coin, would you find a buyer willing to pay anywhere near what jmbullion and others are charging?

I've also heard that an advantage of silver coins having a face value is that if traveling abroad, you can declare that you have $50 in money, when in fact it's 50 troy ounces silver worth a lot more. Is this true?