You do not have to shred anything if you are dealing with Metallix.They use an XRF to determine values.However,you do have to jump through a few hoops to sell to them.But that is common with most refiners.
You are allowed to go and see their facilities,but you are not allowed to watch the proceedures.They claim that you are allowed to change your mind at any time and get your material back,but if you cannot see anything that is going on with your material,you have no recourse if any of it is "skimmed" off the top.Not to mention you will have to pay their pre-processing,and assay fees before you can get your material back.
Just some things to think about.I believe that So Accurate http://www.soaccurate.com/ allows you to watch the entire process,but you will pay a very high amount to have them refine it.I believe the EDI http://www.edirefining.com/electronic-equipment-recycling has a logistics location in north carolina.Their prices are very good,and they can buy the material outright,as opposed to processing it.That way you know for a fact how much you are getting up front,with out any guess work,and you can have the funds almost immediately ,instead of waiting several weeks,or even months.