If the specification is accurate it also follows that, because there is no implementation that recognizes Class B transactions with P2SH outputs to uncompressed public keys as invalid, no implementation can be trusted to display the correct mastercoin balance of an address.

Further, a significant sum of bitcoin has been unknowingly traded with parties which may not even know how much mastercoin they have. Given the possibility that this party has a mastercoin balance to cover the trade, there's no guarantee that it was actually sent to the buyer.

It's really tragic for mastercoin if the spec is accurate, because the loss of bitcoin in invalid mastercoin transactions cannot be recovered, and every single wallet/implementation is useless as a method of sending, receiving, trading, or otherwise interacting with the mastercoin network.