Have to disagree about the 2-door chassis being more rigid. The 4 door's thicker and centered B-pillar actually contributes a lot to chassis rigidity and strength.
And there is a slight weight difference but not as much as most people think, since the coupe's doors are larger and heavier.
There won't be a noise difference if your door seals are in good shape. To be honest, the only worthwhile driving-related difference I can think of is better visibility over your shoulder in the 2-door.
Bottom line is BMW did a great job in making the 4-door as good a performer as the coupe so that drivers wouldn't have to compromise convenience for sportiness, like with some other manufacturers. At the same time they made the coupe more practical than most, it's pretty roomy in the back by 2-door standards. Both are great looking cars. So just pick the one that suits your needs and preferences.