Yeah, on paper it's almost a downgrade, isn't it? It's like night and day tho.
You're absolutely right that other Nvidias & even other 1060s do not show (all of) the same symptoms. I almost wish I could look into the drivers to figure out what's going on here. There are internal block-lists for specific features on certain cards, but with the Nvidia driver being a big black box, we'll probably never quite figure it out. I'm just glad I don't have to anymore.