Since it uses a relay to trigger the power up of the second supply based on power on the first - I wonder what the delay is like? It will bring up second supplies only after first has reached high enough voltage to switch the relay.
I tend to think that jumping green wires is a better approach but this method, though more costly, is a quicker way to setup.
I'm going to bet that most people will be able to setup jumpered green wires in the few days it takes to order an adapter and wait for it to get shipped
