the issue is still endemic to the E-34 and E-32 but less prevalent as some internal changes were made after the early era of the E-23. Still not a good idea to rev aging E-32/34's with that trans in neutral or park "after" initializing trans pressure by driving the car. If you ever go for emission testing which requires that practice....let the car shut down for a full half an hour to let internal trans pressure subside before starting the engine back up and then don't put it in gear until after the test. The ZF 4 HP 22 EH takes a lot of criticism for this much publicized issue. Point of fact is that particular trans out of the entire family of BMW auto box's is my favorite. Mine has 150k miles on it and has never been opened up except for on schedule filter changes and still shifts wonderfully. I just rarely rev my engine for sustained periods after driving the car in park or neutral and can live with that. Don't mind giving it a blast once in a while in park or neutral though...to hear the song of the big six.
HTH,
George