My only real interest in 4K video is to be able to "crop in" without resolution dipping below 1080p. Essentially that gives me 4x digital zoom without any loss of resolution, which is a great thing to have on a smartphone (and gives me one more reason to mothball my stand-alone video camera even for my daughter's school plays). But recording in 4K takes a lot of storage, and then I must bring it into iMovie, edit, and render at 1080. Has anyone tested recording in 1080, zoomed at around 4x, to see if the iPhone automatically takes advantage of the extra pixels to maintain resolution? That would really simplify things. I did one quick comparison of that to a 4K video cropped and rendered to 1080 and it seemed to be the same. I will repeat more scientifically when I have time and post it.