I've got the same setup, and the main reason I'm not interested in this new update is not the mandatory upgrade (as seen in .800 firmware), but rather the forced login before flying.
How does this 900 update affect my ability to fly with no internet connection at all?
So annoying... Mavic supposed to arrive today, it hasn't been shipped yet, now I have a "pending" delivery date with no clue when it will arrive.
Ugh!!!!