I was trying this evening to get some bird pics to try the Dual Pixel Raw Mode but they did not cooperate...a nice deer did step out of the woods near the bird feeder so this is what I was able to get.....
This was 1000mm as I was using the 500mm + 2X TC so I was forced to be at f/8 and I was only perhaps 25 feet away @ ISO 3200 and 1/200 sec

The dual pixel optimizer in DPP really does have an effect

If you look at the fine hair around the eyes and nose I was definitely able to see these come in and out of focus as I moved the optimizer backward and forward.

I would say the focal point could changed by a few millimeters.....could be enough in some circumstances to make a difference

It was very much like making an AF micro adjustment in the range of 3-5 steps I would guess.