Ah, I didn't realize you were wanting to use BRSs one-way.
You would need 2 BRSs to make the relationship bidirectional.
Note that the trust needed for this could be spread out using OP_CHECKMULTISIG.
So you think it could work. A ripple-like network could be establish between payment processors to enable instant payments (the merchant must trust its instant payer).
Now, probably a little off-topic...
If the bitcoin protocol (or a fork) allowed to issue IOUs from one address to another, payment of these IOUs to other addresses and destruction of the IOUs by sending them to the original issuer public key's (this would be a receipt). Could you use this technique to have instant ripple payments inside a chain?
I've have
a proposal to implement ripple in a chain, but I'm not sure it could have instant ripple payments.
Can this technique be applied there with IOUs instead of cash?
I have to think more about it but anyone have some thoughts on it...