It doubles the total opening time, which may or may not be a problem. But outsourcability is so nice it's probably worth it!
About the opening time: could you clarify why there's an extra delay? I'm imagining that Alice would post her anchor tx and Bob would post his payment tx to Alice within seconds of each other. Bob is protected by a timeout, and Alice is protected because her tx is only paying herself at first. They wait until both txs are confirmed, then Bob can reveal his secret. Is this actually slower than your original method?
Rusty.