There are just so many variables, in my opinion, regarding this subject. One important factor is how close your speakers are to the left/right walls. I have found that toeing the speakers in somewhat really helps in this situation, otherwise, the reflections skew the experience.
Another thing I've noticed is that with some degree of toe in, it really helps for those listeners that are off center and sitting in the left/right chairs. If you have the right speaker aime right at the right chair, the singer is not going to be center positioned as if coming from the center speaker.
The other night I had a few friends over and we were listening to various music. I was sitting in the right seat in the front row. I was amazed at how good the soundstage was being off center. The singer still seemed to be coming from the center position, and the various instruments panned from left speaker to right as expected.
Most articles I've read say you should have some degree of toe in, but not Mojo Toe In.
