Here is a recent series of blog posts critical of shared parenting presumptions:
http://www.highconflictinstitute.com/blog/thoughts-on-shared-parenting-presumptions-part-i
http://www.highconflictinstitute.com/blog/thoughts-on-shared-parenting-presumptions-part-ii
http://www.highconflictinstitute.com/blog/thoughts-on-shared-parenting-presumptions-part-iii
http://www.highconflictinstitute.com/blog/thoughts-on-shared-parenting-presumptions-part-iv
Bill Eddy's response:
http://www.highconflictinstitute.com/blog/response-to-comments-on-shared-parenting-presumptions