The 6er is not for hauling people, and as they did not create 6 inches in the rear seats in the new car so, no, it will not allow grown adults to use it for any meaningful trips. Thats what the 6er GC is supposed to be for....
And like you, I do have a need for this more and more, so I'm close to ending my 7 year relationship with the e63 and heading for the F30 in the fall...