I find it very interesting that the Call to Reform now charges various of our sister churches with having an improperly supervised table rather than an open table. That still begs the question whether having EF with a church federation that practices an "improperly supervised table" makes one a false church and calls for secession. I think the approach of our Austalian sister churches is better. Recently (in the context of a decision about the recent Dutch secession), their synod said:

It is a serious matter to allow deformation to go unchallenged, but it is also a serious matter to separate when it is not warranted. The injunctions to remain one in the Lord (eg. John 17 and Eph 4) sometimes even when serious problems arose, as in Corinth, can be read repetitively in the Bible (cf Paul’s letters to the Corinthians, Ephesians, and Colossians). The letters of Paul and the other apostles constantly remind us of this.

A very biblical approach from Australia!