Working the 'bus is good- I've A320,A330,A340- eng, airframe and avionic 'extension'....but only 747 on the Boeing side. Prefer Airbus but that's because most of my (civil) experience is with it...just another aircraft with some different things to watch. Airbus books are a lot lot better than they used to be and, if you take the time, are pretty logical and usually good value. . .. .I've found most people who slag the Airbus' off either haven't worked them or don't know the systems well enough. Good beast...but not perfect.