Didnt read thru it all (8 plus pages) but I have both with the M8 and the G80-- plus I had the AWD F90 M5.... its ironic but now that I have the G80 I seem to have more dig lineups than ever on open streets with other cars where I wish I had AWD. But then when driving thru nice turns and bends, the G80 steering is better than the F93 AWD chassis set up for obvious reasons. The BMW AWD system in the M cars has been incredible vs the likes of my 2 RS7's, and even a W213 E63S.
Its nice to have choices.
Not sure if this was posted in the 8 pages but a pretty good video on AWD vs RWD with a reasonably objective analysis on a wet and dry track.