My experience of the Airbus FPV is that it is not as "instant" as Full Wings suggested, based on his B777 experience. (Perhaps the Boeing, being newer, has faster computers to figure it all out - the rest of his reply was pretty comprehensive). The Airbus' FPV have a bit of lag and wander - only a bit, mind - so it should be used as a performance instrument, ie set the pitch attitude with th AI, let it settle, then confirm that you are getting the flight path and track you require. It's a great tool but you can be suckered into "chasing" it and therefore not quite settling down on a desired flightpath. Any other 'Bus drivers agree or is it just my shaky hands?