No, it is my last name )))

I drive about 12-15000 miles p/a and if I get diesel fuel economy will just cover twice higher taxes for diesel, but never 6000 euro + for diesel X6, but as you said I can sell the diesel for higher value and return that 6000 euro in future. So economicaly it is absolutely the same to have 3.0sd or 3.0TT
+ of sd version is higher torque and rarer fuel station visits (more miles on one tank)
- are engine sound (IMHO) and less sportiness of diesel.

After the review of Steved I think I would also stop on diesel, as it is also going to be a family cruiser, but I want to make a test drive and decide can I stand for 3-4 hours of the diesel and get used to it.
Thanks for very good and complete unswers.