**** JUST GOT THE OFFICIAL UPDATE FROM BMW DEALER ****
The update's done, very painless, once the dealer got the authorization from BMW it took less than an hour to do the physical recode. Here's how it functions:
Remembers last state always.
If stop engine in Comfort mode, ASS stays off on restart.
If stop engine in Sport mode, ASS stays off on restart.
If swap mode from Comfort to Sport mode, ASS stays off.
If swap mode to Eco Pro mode, ASS turns on.
If stop engine in Eco Pro mode, ASS stays on on restart.
In a nutshell, behaves as you'd expect. You can jump between the Sport and Comfort mode as much as you want, ASS stays off. So long as you turn ASS off once and never put the car in Eco Pro mode, it'll never bother you again.