Personally I'm pretty sure most, if not all, batches of FBI coins will sell for a premium. Not because the coins are "clean" or "collectible", but because the investors would happily pay more to avoid slippage.
Think about this hypothetical situation:
20 individuals bid on the coins. I think most investors would bid for more than 1 batch of coins, with a number of bids below market and a number above market price. You only need half of the individuals to make a single bid over market price for all the coins to sell at a premium.
In other words, if you think ALL of the coins will sell at a discount, then that means that NOT A SINGLE BIDDER will bid over market. Pretty unlikely I would say.
The actual number of bids was 63, go figure.