None of those options really cover it for me- the duration of the scene was an issue of sorts- I felt extremely uncomfortable, horrified, upset by the scene, and obviously its duration played a large part in that (11seconds wouldn't have had quite the same impact). I do think it was necessary (if anything, it's the only thing that makes the ultra-violence at the beginning of the film make any sense), and it should have been that long, since the duration is a major part of its impact.
As others have said, the whole point of the scene is to make you witness the event with the maximum possible amount of empathy/horror, and I think it achieves this very well indeed. Whether or not people feel comfortable with this is a non-issue in my eyes, people can (and did) walk out of the cinema if it's too much for them. The fact that it did disturb people that much is (to my mind) a tribute to the skill of all involved in the film.
But now I'm asking myself the question- how much could I have taken, where's my rape-scene threshold. I don't know, but I imagine if it had gone on and on and on I too might eventually have had to leave.