Gotta admit I love having the 4G backup, it was only when my server lost connectivity (its routed exclusively over DSL) that I knew anything was wrong. I was having a nap when it started, mum was blissfully unaware.
For some reason the VoIP wont reconnect over 4G though, not sure what that's about. I don't actually use it yet, its just there in preperation for the future.