I don't understand why anyone would want this instead of 6DOF TIR for a flight sim. Being able to look out a side window is actually useful in the game, while this would just be sort of cool. Given the choice between 6DOF cockpit and a cool 3D effect I'd choose 6DOF any day.
Correct me if I'm wrong (haven't thought too much about it), but couldn't you get the best of both worlds with TIR? You could use x,y,z the way this guy does it, while using rotation around the axes to rotate the view. The Wii system can't do that because it only has 3DOF (if I'm counting correctly).