Interesting article.
Van Ref only "advises", final call is with the man in the middle & is only used for key decisions, red cards, penalties and goal incidents.
Says that close calls will still be close calls, so won't end all debate and its up to match ref to ask van ref for help - no manager challenges.
Interesting that they have found that the more inexperienced the ref, the more they have asked van ref for advice.
They are hoping to get go ahead from FIFA to officially trial the system next season. It will be on agenda of next Laws meeting very end of Feb.