Folks, there are so many variables on this!
If you are shooting big animals in mid water, you will not notice the 10-17mm's distortion and poor corner performance, even with a small dome. If you are shooting reef scenes, with details in the corners, you definitely will.
My conclusion from using the D800 with a 10-17mm and a TC was: "I tested the D800 with a Tokina 10-17mm fisheye and a Kenko 1.4 x teleplus Pro 300 teleconverter. The combination produced vignetting, and image quality was significantly degraded."
http://wetpixel.com/articles/wetpixel-d800-camera-review/P5
Put simply, the more optical elements you add, the stronger the likelihood that the image will be degraded.
I have experimented with the D810, Sigma 15mm and the Kenko Pro 300 1.4 X. It does "de-fisheye" the image somewhat (like the 10-17mm at 17mm) but the image is definitely not as sharp. For sure, this is a pixel peeping difference, but it is noticeable.
The best dome option for any fisheye lens with a full frame camera is a 6" or 170mm. The 4" domes are great with cropped sensor cameras....
Adam