We have done 50/50 since my DC was 3 year old. They are now at school and it still works really well for them. They are happy and well-adjusted to it.
Spero What are these 'huge practical difficulties'? I find, as a parent with 50/50, your use of the word 'shunting' to be insensitive and mildly offensive. My child is not, and never has been, shunted. Some people may have practical difficulties, although out of the 6 families I know (myself included) in my peer group who do 50/50, no-one has huge practical difficulties so I'm completely unfamiliar with them. Maybe you can tell me about the difficulties in our lives? 
The pain EOW would have caused my child means I could never have considered it for a minute, even if I didn't have other reasons for deciding to do 50/50. The EOW setup is a throwback from the 70's and 80's. I am sure that maybe other families are different and maybe it doesn't adversely affect other children badly, but it would really have messed up mine.
^The sole custody model has, surprisingly, come under relatively little scrutiny in Canadian government reports: ?It is ironic,? writes Joan Kelly (1991), ?and of some interest, that we have subjected joint custody to a level and intensity of scrutiny that was never directed toward the traditional post-divorce arrangement (sole legal and physical custody to the mother and two weekends each month of visiting to the father). Developmental and relationship theory should have alerted the mental health field to the potential immediate and long-range consequences for the child of only seeing a parent four days each month. And yet until recently, there was no particular challenge to this traditional post-divorce parenting arrangement, despite growing evidence that such post-divorce relationships were not sufficiently nurturing or stabilizing for many children and parents. . . There is evidence that in our well-meaning efforts to save children in the immediate post-separation period from anxiety, confusion, and the normative divorce-engendered conflict, we have set the stage in the longer run for the more ominous symptoms of anger, depression, and a deep sense of loss by depriving the child of the opportunity to maintain a full relationship with each parent.?
Herein lies the crux of current child custody and access policy debates. It has somehow come to be regarded as developmentally ?correct? to award sole custody to one parent, usually the mother, with twice-monthly weekend access ?visits? with the other parent, usually the father. Yet there is overwhelming evidence that such an arrangement disregards children?s physical, psychological and social needs for both parents in their lives.^ - Edward Kruk, Associate Professor of Social Work at the University of British Columbia, specializing in child and family policy. Excerpt taken from 'Child Custody, Access and Parental Responsibility: The Search for a Just and Equitable Standard.'