Lots of post about the flush or not to flush. Here is a thread where the X owner flushed the fluid and seemed to get good results.
http://www.Xoutpost.com/bmw-sav-foru...nderneath.html
Most posts say that changing the fluid is just a band aid fix and you will need to replace the tranny anyway. Its also said that the fluid is lifetime for the tranny. But lifetime seems to be identified as 100,000 miles.
My tranny was just rebuilt with 75,000 miles.
I say flush it and see what happens. Let us know what the results.