Rob,
Thank you for your input. I do not get to try these items so I have to rely on what I read.
The Ninja has a lower-res screen.
The D800 does not allow you to zoom in to 1:1 while recording. I would have hoped that monitors would allow that, since they are receiving a one-to-one signal. Instead of downsizing to fit into the low-res display, they could just crop, it seems to me. Not sure why they’re not designed that way. In fact, I’m not sure why the camera is not designed that way.
EVF is definitely better than loupe over the camera LCD screen, right? The only plus I could think for the loupe (without having tried) is that it gives you three points of contacts.