I currently own the D810 with some nice glass and the EM1 with most of the Pro lenses and especially the 2.8 40-150 is the lens that keeps me in m43 again and again.
Currently I am on family vacation in the Austrian mountains and guess what I took with me - the EM1 with 3 lenses and not the Nikon. The Nikon would have been absolute overkill and hardly I had taken it out for some hikes.
Had I already the XT2 in my arsenal, I most probably would have taken this camera because it can nicely fit my requirements for small, light and portability, but at the same time has some wonderful pro lenses and tele lenses too if that is required.
I guess this shows the point ....