No one should really trust large amounts of money in physical coins manufactured by others containing plaintext keys, but ones with BIP38-encrypted keys are fine if generated using an intermediate code, or where an already-encrypted key is supplied by the user, since in that case even the manufacturer can't decrypt them.  I have seen some physical coin manufacturers that offer such options.

(Note that Casascius is the one who developed this standard, why would he have done this if his business model was to keep the private keys?)

BTW I recently posted a fork of the BtcAddress reference implementation that adds support for BIP38-encrypting existing private keys...
https://bitcointalk.org/index.php?topic=355471.msg3802614

Cheers to all... And Mike, I hope you work things out so you can continue operating.