I just finished watching this video carefully and noticed something on the phantom 4. In the segment where they slow motion the inside of the craft, pause and look at the motor mounts. Top and bottom work in conjunction. This is a phantom first. This has two pluses structurally. For starters, in theory, it's a far stronger motor mount which uses top and bottom of fuselage. The added bonus is that by using top and bottom to hold the motors this also does the job of those two screw holes we kept cracking on the phantom 3. I could be mistaken but from the video it looks like a top and bottom motor mount.