It's true the D4 looks sharp in crop mode, but none of these DSLR's, (including the 1 DX) is going to look great at ISO 25,000 +. They will for [u]stills[/u] under the right circumstances, but definitely not video. The noise levels will make the footage worthless for doc work. If you want extreme ISO's, you'll have to look at the C300. That being said, the 1 DX is the single best low light full frame DSLR availible right now. The D4 is great in low light as well, but remember it's soft. We'll have to see if the 4K 1 DC DSLR ups the game. Should be close.