Yeah, definately
Don't touch the brightness setting, this really interferes with things.
The HDR brightness setting is broken below 1000 nit, the same as Origins (which I had missed).
The HDR brightness setting provides a a simple roll off to the maxmium value selected, this helps to provide a smoother graduation towards something like the sun, rather than having a clipped round orb in the sky.
Based upon what I can see the tonemapper doing, I think the paper white's in game "default" would actually be 80 nits, any adjustment you make is actually adjusting this point in the image. In order to achieve this , the tonemapper will actually brighten the darker areas as you increase this (hence the feeling of overall brightness increase) and further increase the peak brightness, liklely to ensure that contrast and dynamic range continues to exist between the 2 different white points.
So with this in mind, the lowest you want it on is 80, which is certainly what I would recommend if you are going for a "reference" setup.
If you prefer a brighter image (who doesn't) I would go as high as 200.
But as always, the brighter you make the image, the more HDR overhead you are burning up, particually for OLED uers, increasing the paper white will make shadows and near black a little lighter,