I'me a D810 shooter (and D7100). No help here. And I have several friends I've tried to get to try the Magic Lantern firmware, but none have bit. Besides, while I don't generally have a problem with rooting and hacking, there is a big difference between OEM supported functionality and hacks.
The 6D basically becomes a totally different camera with Magic Lantern. IMO it's the best thing in a while that happened for Canon shooters. I loaded it with no problem on my 6D, and loved it. To me main benefits:
True working intervalometer from the camera. No other camera has this with full function, i.e. you can take the exposure past 30" as all other solutions rely on the camera's timer, which IMO is quite stupid. This includes Fuji, Nikon, Canon and Sony. It's obvious they never spoke to anyone working at night.
Raw video, really interesting and much much much better than the standard video from the 6D. There is a ton already written about this issue.
Dual iso, once you get the hang of this it's excellent and got much better with the last iteration from Magic L
Focus peaking, a it hard to get used to, but it works
There are so many other features that it really makes the 6D a totally new camera. Sad to see just how much Canon could have done, but chose not to. And it's not just Canon here, it's all of them. They are so worried about the effect on upsell.
Classic example is the Cini 1dx and 1dx, 4x on the Cini version, but not available on the 1dx. Sad.
Paul