Isn't it possible to create one token pegged to BTC using an escrow address to make it possible to also get a buy side? Send BTC so the escrow address, get Mastercoin BTC tokens back to be traded in the order book. It should be possible shouldn't it?

Also did you reach out to any of the other coins to see if there is developers to help integrate in omniwallet? Peercoin and Litecoin is already mentioned and Feathercoin and Dogecoin should also be valid options. Maybe also Quark and Peercoin.