Would you also be so strict on the Presbyterian distinctiveness with the Sabbath, images, , acapella worship, exclusive Psalmody, the Filoque, etc?
I’ll gladly answer this, although most of these questions could have easily been answered by consulting the Westminster Confession of Faith, but I’ll add to each answer:
Sabbath: don’t work on it.
images: contrary to a lot of young-pup critics of the Reformed faith, the Reformed faith does not preclude images of non-divine entities. I understand the EO take on images: it is not imaging the divine nature qua nature. However, one must immediately respond that neither does an icon image the divine hypostasis, either, because the wood and painting is not the divine hypostasis. The divine person incarnate in matter could be worshipped because the matter was in the divine hypostasis.
acapella worship: some do; some don’t. The same with Exclusive Psalmody. Already I can anticipate the charge, “Look how chaotic the Reformed world is. They can’t even agree on worship.” Well, I am pretty sure the local Greek church electronic keyboard, is not the same church as what _________________ (insert name of great saint) worshiped in.
Filioque: The Reformed world officially accepts it. However, during that time period one can only fight the battles which are currently raging. The Filioque, for better or worse, was not on the forefront (and I think it should have been, for thus could the Reformers have dealt a full blow to Rome). Most Reformed systematic theologies do a terrible job on this (Turretin merely asserts every point; he doesn’t even begin to argue the question). To be fair, though, they’ve never had a reason to develop it.