This is from BMW own internal site - It's their TSB (Technical Service Bulletin) - You can make you own mind up from here ! ...
BMW has a TSB (SIB240305) for the BMW E60 (New 5 Series) and E63/64 (New 6 Series) with the same ZF 6HP26 transmission, that defines IDENTICALLY the symptoms as outlined above.
BMW TSB - SIB240305 bulletin:
Harsh 2-1 Downshift
E60 (545i); E63/64 645(Ci/Cic) with 6HP26 up to 04/05
Customer may complain of the following:
An excessively harsh 2-1 downshift when decelerating to a stop, or
Transmission "bangs" into gear when accelerating from a full or a "rolling" stop
(vehicle did not come to a complete stop).
On a customer complaint basis only, reprogram/recode complete vehicle using SSS
with CIP on-line update 17.01, or higher.
Transmission temperature must remain below 50 deg C and trans shifter must be
placed in P position prior to the start of CIP programming.
In addition read about one BMW Owners' experience and discussion with a ZF Engineer on the Lurch variants - a simple technical admission of the Lurch by ZF : Steptronic Slam is Back - E60 Forums
Food for thought eh ????????