[p750mmx]

Thanks for testing this.
Here is summary of various test down to the important stuff that counts. Please correct me if I'm wrong.

Using Kaby Lake you are getting very good picture 3D and low CPU interlaced mode on both ports HDMI 2.0 and 1.4.
On port 1.4 you could easily switch within Kodi to 3D Hardware (frame packing) or interlaced (3D upconverted to 4K by PC).
From your observation picture is better when interlaced mode is selected. This will apply only to 4K TV sets with passive glasses.

That sums it up. Output with Interlaced setting is at least equal to hardware based setting on the 1.4 HDMI port, but I prefer the 4k resolution setting as standard for desktop and Kodi by using Displayport > HDMI 2.0a, it gives me the best "overall" picture with 3D and (4k) media.

I would like to point out that my experience is only based on the hardware in my footnote and this is not a "general" Kaby Lake NUC and TV setup.