the i30 Eidtion has the windows blacked out look nice.
do you know how dark the Edition is? when you said 'Limmo black' in your first post is that the same colour?
i think if you have heart set on it then just do it, its just tint and therefore ( i do believe) not a permanent fixture to the car, so if you ever decide its too dark you can always change it. you're the one driving the car.
personally i would get the four windows done as that looks even better than just the rear windows, but here in aus its also more of a need with the heat we have.