Merlin,
I've no inside track on this, but we tried to set up something similar a couple of years ago. The problem we had was that if the broker goes belly up then the money goes to the brokers administrator (whereas the cancx fees should go to the operator) and if the operator went belly up then the money goes back to the broker.
So, not a lot of protection for the operator. I'm sure someone is trying to get around this point of law, but I don't see any operators going for it until they do.
PB