Don, totally agree, I currently use the D5. My dealer is so wonderful that when I purchased my Arca eons ago, he gave it to me as a loaner until the eModule (yes that is how long ago it was, now we have moved on to the eModule Cloud) came in. Well pigs are flying, and my eModule Cloud is likely next week. After playing with a production version last week, I am super impressed with what it can do. Having said this, I love the D5, and am going to buy it regardless of the EMC. It is a great backup, and the screen provides a great alternative to looking for the damn dot in sunlight. I think it is especially useful on the arca given the focusing strategy employed, and not knowing first hand, but I would expect the same level of usefulness when using HPF rings - no point in knowing distances to multiple points of accuracy if you cannot set it on the lens.
I also find it extremely useful with a couple of different DoF and HFD apps for iPhone/iPad.
I am also looking forward to using it on the golf course this year, I think my game has suffered tremendously due to the lack of accuracy of my current SkyCaddie
Hope Guy doesn't see this, there will be a run on D5's given the multiple usage scenarios!