I am trying to understand this thread, forgive me if I have missed something - Beosystem 2 can 'handle' full HD because quite simply it has nothing to do with scaling and there is no DVI output socket to go into it (can't speak for the Beosystem 1).
If you have a 1080p panel, Beosystem 2 can 'handle' full HD so long as your source supports 1080p - Beosystem 2 only acts as a switching box, you must have the latest SW level.
Same for the BV5, it is just a DVI card that slots in the side and acts as a switch with your source driving the panel directly, but you also need scart and digital phono in both scenarios for audio.
Sorry if I have missed the point completely!