Good evening (morning technically):
That looks a lot like one of Model Memories PRR offerings, or it is a scratch build. I have seen several good examples of scratch-built Pennsy catenary, for the same reason you stated: simple and elegant, which was often the case with the Pennsy itself.
EDIT: I found a better video of the Brandywine system here. That catenary has a scratch-built look to it the more I study it, with a nice static shot here.