nice roughbeast, you will definitely see a massive improvement over the voda router. i haven't gone as far as you with the failback for 4g connection or voip, never used the phone anyway, but have had a rock solid connection since i switched to my own.
only time it has been off or dropped that i'm aware of that is, was when i unplugged the router to sort out cables behind my tv cabinet.
getting full 500MB, going to 560MB most of the time, up and down.