Vocals will carry both melody and the usual semantic content that goes with language - which of those you prefer emphasized in your music in subtle ways can to my mind be a similar question of preference as whether you like your bass boosted or not - if indeed more subtle. Though I can also see that the mind has been made up in this thread by and large that all headphones should be neutral (won't happen, this would put most manufacturers out of business, would it not). I for sure prefer neutrality as well, but not to the point of dictating it quite so harshly.
Having said that, the floor is still likewise open for discussion on the effects of this left/right divide on the study presented in the Harman paper, a study in which this variable was not controlled for apparently. Would people have a preference to hear vocals primarily in either the left or the right ear? I'll also note that the S & W article I've been referring to was published in The Lancet; I'm sure they put more than a cursory thought into it.
Edited by vid - 7/16/13 at 4:59am