Nice job on the coins, they are cool. However the trust factor is way to high. I went down this road myself when I created the gold plated CoinBit
http://CoinedBits.com.
The original consumer has to trust that Casascius isn't selling them a zero value coin. The circle of trust then gets wider if the original consumer tries to trade the coin. The second person receiving the coin now has no way of verifying the coin originated from Casascius.
Counterfeiting this coin would not be difficult, and would be extremely lucrative if the Casascius coin gained adoption.
This is why I ended up keeping the CoinBit as a novelty or souvenir coin.
If your CoinedBits had a flat surface about an inch in diameter on them, they could be made to contain bitcoins and people would still happily buy them.
If someone wanted to throw resources at counterfeiting the coin, seeing as people are already willing to pay a 25% premium and shipping on top of that to acquire the coins, why wouldn't they just throw those same resources at legitimate coins and not risk getting their cover blown? One could just as well counterfeit Bitbills or FRN's. Further, people are going to be peeling and redeeming a percentage of the coins... until people start complaining in the forums about the existence of counterfeit Casascius bitcoins, for the time being, one can be pretty sure that the Casascius hologram is an accurate indicator of origin.