Hi ! Welcome. Funnily I went through your process some time back when I eventually bought a BMW 6 series (Still the best car I have ever owned)(had had various Mercedes including AMG) but then I decided on a two seater convertible and went through the process again.
Tried the Porsche and the SLK but not the TT! looked at a couple of others but came to the conclusion that firstly the cabin on the Z4 is the best place to be, the drive and power trade off from the Boxster and the SLK AMG was worth the lower power of the 3.0ltr. Overall I felt far more comfortable in the Z4. My car is quite highly specd! Having owned it now for a few months you will not be disappointed, the girl can lift her skirts when she wants to push it! with the added Sports mode you can have some fun, very few of us have the skill to push these cars consistently to the limits, and on today's roads limited opportunity.....Sadly I have been spanked a couple of times by straight line speed from traffic lights but not enough to embarrass me!!!!! There will always be someone with that extra oomph!!!
One of the other reasons I dropped away from Mercedes was actually very poor reliability across a number of models, even when Mercedes damaged one car and were never able to repair it properly (SLK AMG new roof).
Always said I would go back to a 6 series
Last edited by 645/333; 08-01-2012 at 04:14 PM.