I was ready to do the tranny change myself, had one lined up, did my research, got some tools and then realized my warranty covered ..... freakin bonus... BMW actually changed it twice as the first replacement had some strange hesitation. Dropped it off in the morning and picked it up same day - evening! Nice shiny new unit underneath. If you need anything at all look me up. There is nothing special about the tranny - its a ZF unit and there are 10000's out there.
cheers