Does Sunrise supply the settings at the same time? I wanted to order the Zyxel separately via Digitec and didn't know that Sunrise also offers it officially....
Have you found a way to back up the Sunrise firmware? At some point you have to return the thing and then it becomes obvious if the wrong firmware is on it. That would be the primary challenge for me.
You also have to extract the options to be set or ask Sunrise for them (if they give them out).