So a couple of weeks ago on the podcast Dan said he was planning to play the game co-op with his girlfriend, him on pc, her on Xbox, using the same copy of the game but with her using her profile on his home Xbox. Does anyone know if this is actually possible as it sounds like a really fun thing to do with my own gf.

There was a thread about this maybe 2 days ago and a dude managed to make it work yes.

that's the only way it works on 2 devices at the same time. if you try to launch the game on separate devices with the same account, even with 30 seconds of quitting the other and launching on the other it still locks you out.