Thanks ReadOnlyCat, for your very wise words. You´re exactly right: Developing a polished demoversion just for the show would take away precious time from the "real" development of the game.
Also, as you say I´d have to use some "hacks" to make some portions of the visuals work in this early stage. That´s exactly the opposite of what I´m aiming for: proper, elegant and bugfree code that is glitchfree and works reliably. This will result in a gameplay experience that is real smooth and enjoyable.