JA, your a7RII looks a major step up from my a7II in terms of High ISO.  I've been disappointed with the High ISO of the a7II compared to most of my Nikon FFs.   The 80-400 afs works quite well on the Commlite AF adapter.  If I pre-focus to the general distance it is very fast to lock on. Still not up to action shooting. 
Bjørn, I would expect adapters to keep improving particularly if the major lens manufacturers get into the game (ala Sigma's new adapter) .  Using adapters is enjoyable due to the lens selection available.  The Df brought me back into manual focusing and I use MF vs AF about 50% of the time now with the Df.  It is a pain having to set the FL and not having EXIF but the images work.  Scouting for old lenses is also enjoyable and cheaper ( I did not say 'cheap'  

 ) . 
We are off to the Thar Desert (Rajasthan) next week.   My wife and son have it easy.  Both shooting EM1's and 6 lenses between them.  I'm taking the Sony and Df with a selection of Sony, Zeiss, Nikon, Voigtlander and Leica lenses.  Fortunately the carry on weight is cumulative  for the family  

 . The Nikon and 3 lenses weighs close to the same as the Sony and 7 lenses.  The only long lens will be the Olympus 40-150 2.8 (and TC1.4) .
It is all about enjoying taking photographs  

I did think about taking just the Sony but I am still not that confident in the Sony and the Df is just so good with that 16MP sensor and I can still use CNX2 .
Tom