@MW: I don't disagree with you making this point here: "But Westminster represents later doctrinal developments and a more articulate 'system.'"
That is the Presbyterian argument, and I expect it to be made by you, as a confessional Presbyterian. You have, after all, sworn to believe your confessions.
Not everyone in the Reformed world agrees. Actually, I'm a lot closer to you than many, and my only real area of disagreement with Westminster is church government, not the examples you cite.
You also hit the nail on the head here of why people in Dr. Joel Beeke's denomination and seminary were willing to accept the Westminster Standards:
The following point you make addresses why many others in the Dutch Reformed world, including the Canadian Reformed and Protestant Reformed and some others, object to points on which the Westminster Standards go beyond the Three Forms of Unity:
I would prefer to let the Protestant Reformed and Canadian Reformed people who are here, and Netherlands Reformed people (if there are any here). explain the details of their views on covenantal theology and related matters. My understanding is they don't object to WCF people subscribing to their own confessions but want the freedom to hold views which they have held for a century (in the case of the Protestant Reformed) and which were at the center of the deposition of Klaas Schilder in 1944 when the GKN Synod met to try Schilder, who was at the time hiding from the Nazis and unable to defend himself.
The issue of the "continental Sabbath" is, I believe, largely a red herring. Most people today I know who advocate a "continental" view of the Sabbath are not Dutch Reformed, but rather Presbyterians in the PCA who use it as an excuse to take an exception to the Westminster Standards. I'd say different things if we were in the 1600s -- there really WERE reasons why the Pilgrim Church at Leiden felt the Dutch were weak on the Sabbath and left to found the Plymouth Colony in what became New England! -- but that today is an irony of history that the common Dutch Reformed practice is stricter than the text of the confessions require, while the common Presbyterian practice (meaning in the PCA) is looser than the text of the confessions require.
But Rev. Winzer is right. Go to Ursinus' commentary and you'll find a high view of the Lord's Day. The commentary goes beyond the text. Ursinus was not stupid and he knew he has working with a government and a people who were fairly new to Protestantism and their previous instruction had been Lutheran. He put into the text a strong statement about what the Bible teaches on honoring the Lord's Day but didn't bind the conscience of people who he knew would disagree by putting into the text of the actual catechism things that he put into his commentary on it.
I think much of what I have said to
@MW will also reply to Scott, but I want to address this specific point:
Westminster goes beyond the TFU. I think that point is beyond dispute.
I do not believe the confessions contradict each other in the sense that "it in fact impossible to subscribe totally and without exception to both the Three Forms of Unity and the Westminster Standards."
There are some in the Dutch Reformed world who do say that and have made a point of attacking the Presbyterian standards. That has never been my view, and I think that view has largely died out. In earlier generations, that was generally the position of more "progressive" people among the Dutch Reformed back when people on the progressive side of the CRC still believed, or pretended to believe, in confessional subscription. The more conservative people in the Dutch Reformed world who disagree with parts of the Westminster Standards have generally said, "You have the right to believe that, it is within the Reformed tradition to believe what you believe, but it goes beyond our confessions and we are not bound by your confessions, but by our confessions."
It's a one-way street, not a two-way street, between the two traditions. But even that is limited. A conservative Presbyterian doesn't hold doctrines that contradict the Three Forms of Unity in principle, but the Blue Bell controversy in Philadelphia, when the OPC lost a church that split two ways, part of it ending up in the Canadian Reformed Churches (technically the Canadian and American Reformed Churches) and part of it ending up in the Protestant Reformed Churches, shows not only that the confessions are different but also that the Dutch Reformed don't fully agree themselves on what the Three Forms mean on the covenant. Schilder and Hoeksema got along well personally, but the doctrinal differences were real.
(And yes, I do know the recent history of Blue Bell. It's not relevant to the point I'm making here, and I don't want to get into a very difficult local church situation of two small churches trying to find a way to continue in an increasingly liberal part of the country where young people leave for better opportunities.)