Good writeup.... I don't think you said anything I wasn't expecting though, other than the "reasonable" ride in the M.
"Reasonable" is relative I think. The whole reason I traded in my car, chose air suspension, and chose to get 21s instead of 22s.... was because the roads are so bad here. I think that "my" version of an X6M here in Belgium.... would be intolerable.
Besides..... I can get a roof rack if I want.... I already bought a trailer for my motorcycle.... and I can even fit my 200lb dog in the back of my X5.
And.... I've already lined up professional dynotuning as soon as this coronavirus thing ends..... which is a guaranteed 680 hp
I'm pretty happy with my X5 M50i
Not as "flashy", but otherwise, an all-around better car.