Transmission Control Module Replacement
In the US there was an undocumented fix that involved a DME update, some call it an e-gas update. I have had this done on my car and many others in the US have had it done as well. This did seem to improve the throttle response such that, if the transmission was in the correct gear, response to throttle input was pretty good. As far as I can tell though, the DME update did nothing for the transmission shift mapping. It still seemed to be in the wrong gear far too often and slow to get to the correct gear.
I have recently seen reports of the transmission issue being addressed with a replacement of the Transmission Control Module. Supposedly the model year 2005 version, possibly part number 955-618-022-11, has significantly improved shift mapping. One dealer has reportedly replaced the module on several customer cars who complained of the throttle response and they have all been happy with the result. All delayed throttle response symptoms were gone. Another dealer took the 05' module from a donor vehicle and installed it in the older car with good results.
I don't know if replacing the transmission control module will cure this issue or not. I am reasonably sure that the transmission shift mapping is not software updateable so replacing the control module does make sense. Whether or not the 2005 version has solved all the issues, I don't know.
I believe there will be additional information and developments on the control module replacement over the next few weeks. As I become aware of new information I will post it here. I would certainly like to hear from anyone who has had this done and what their experience has been.