This is something that has always puzzled me about hard money advocates in general. They tend to be numismatists, but in critical times, it is unlikely that the numismatic value of many of their assets will hold up. They may lose their shirts on a sizeable portion of their assets that they claim to hold as a hedge.
My coin collection is not held as a hedge.
The most valuable coins may change little with the spot market because rarity is the key factor in their value, not the bullion content.
Comparing apples to oranges, the last Van Gogh painting sold for far more than any coin, and had vitually no intrinsic worth (canvas, paint, wood), whereas the rarity and artistic value made it worth tens of millions. If wood, canvas, and paint were traded commodities, changes in the value of paint, wood, and canvas would affect its value very little.
In hard times, an ounce of gold is an ounce of gold, and a collector would be watching even then for coins which would command a high numismatic premium when things improve (call it a 'down market--buying opportunity') and using the common issues and lower graded coins for trade.
In the most critical of times, I would put more faith in my 'semi-precious metal' portfolio, anyway.