Ok...the camera arrived Thursday. I've been taking a few test shots with various lenses and I'm absolutely blown away. It's breathed new life into some of my more neglected lenses. My Sigma 50 1.4, which was always hit-and-miss on the D700, is producing spectacular results on the Df. Also, I've got an old Tamron 24-135 that has become a strong performer once again.
I had been considering selling both of these lenses, but I think I will hang on to them a while longer. So far, I've been pleasantly surprised by this little camera. All the complaints about the poor AF performance in low light are non-issues for me so far. I'm still adjusting to the ergonomics, but it's definitely the best performing camera I've ever used. Once I get fully adjusted to the camera, I will post a few photos.