What is the role of the custody evaluator?

I just finished reading an excellent article  by Gary Direnfield, MSW, RSW entitled Unraveling Custody/Access Assessments/Evaluations.  In this article Gary provides his reader with a succinct explanation of the role and responsibility of the evaluator as well as explaining when and how custody evaluations come about.  The important take away is that parental action or sometimes, inaction lies at the base of the need to call in a custody evaluator and that always it is best for parents to come to their own parenting decisions rather than place the burden on the Court.  Further, the evaluator is not the decision-maker, that is the role for the judge.  Instead, the role of the evaluator is to gather facts and then make recommendations to the court regarding the parents' relative parenting strengths and weaknesses in light of the specific emotional, developmental and other such needs of their children.