Ok, so I just compared the two again 25X, 19X, 10X, and low power. 25X was easy because the magnification ring on both scopes is engraved with a "25" but after that it gets a little iffier because they are engraved the same. The NF is engraved with "19" but I had to go just past the "20" on the XTR III, same for "10", the NF isn't labeled so I lined it up between "9" and "11".
Now all that being said, the object that I was viewing was about 1,200 yards away with an adjacent field on the left side and trees the other side. Due to my positioning I also had a power pole about 75 yards away that will come into play later.
25X: It was really too close to call between the two, what I could see in the FOV was pretty much the same.
19X: Still pretty close to call definitively.
10X: The edge goes to the XTR III as the wider FOV is becoming more noticeable, I can see a little more into the adjacent field and a good bit of the power pole in the right side of my field of view. With the NF the FOV is more narrow and I'm not seeing as much of the power pole.
Low power (5X for the NF, 5.5X for the XTRIII): Yeah the difference in FOV here is pretty stunning, the Burris is much wider compared to the NF, I'm seeing way back to the corner of the adjacent field and the whole width of the power pole and then some. In the NF, I have about half the pile of lumber that's in the back corner of the field in the left side of my FOV and can't quite see the entire width of the power pole in the right side.
In terms of edge to edge clarity both scopes are good, I didn't notice any major edge distortion or anything in either scope. Again, the eye box is a lot better on the Burris at just about every magnification compared to my ATACR but the ATACR had better IQ in my opinion, that being said the difference really wouldn't hold you back.
So there you have it. In my opinion, both have great fit and finish, perfectly functional, tracking is spot on. An edge goes to the NF for overall image quality but concedes some ground to the Burris in terms of eye box and FOV at lower magnification.