Gold and Silver coins as "Legal Tender"

What do you think of the following?
http://www.mineweb.com/mineweb/content/en/mineweb-political-economy?oid=182807&sn=Detail

I actually like the South Dakota model (which didn't pass) which proposed:

U.S. Government-minted gold and silver coins legal tender that could be used to pay state taxes at their market value

I have a dozen or so Standing Liberty Quarters with the dates rubbed off that I would love to cash in for their silver value.

So, rather than being spent at their face value, for example, your Standing Liberty Quarters...could be spent and recognized as, say, eight dollars...if the silver price and content matched an amount of eight dollars?

The basic problem with this would be that one would need a scale to know their weight...and what percentage of the content was silver or gold for alloy coinage...or would this apply only to solid silver and gold coinage?

Since no person could be COMPELLED to accept them as such, this is a good thing. It would be bad if people were COMPELLED to accept what amounts to a quarter...as being eight bucks.