My problem is gonna be to do with a swinging camera, I think its gonna make a huge difference as to what direction you'd expect to move in - and what it is actually set at. (if ya see what I mean !? )
Yes, I think I do see what you mean. Are there any restrictions you can put on the camera itself to fix the problem? Perhaps, always viewing from the same horizontal angle, or horizontal range? As the camera revolves around the object, you can always rotate the control axes, so that, for example, moving right on the controls always results in the object moving right relative to the viewport. This is how many (most?) 3D games do it. (I'm thinking of a lot of platformers right now.)
simonh, that was a very nice article you linked to.