The Z4 is a keeper for sure. Its got classic proportions with a very sleek design that will keep it looking good for a long time. I plan to keep it for at least the next 5 to 10 years if it remains trouble free.
No worries Rob, I too was looking for the ultimate throttle map for my DCT and have gone back and forth between the Cobb ST (Standard Throttle) and LT (Linear Throttle) maps many times. I installed Sprintbooster later and tested again with all the different maps and finally settled on the Stage 1 LT with the occasional use of Sprintbooster.
The ST throttle with the Bmw stock tune worked fine as it seems the engineers were compensating for the turbo lag by front loading the throttle curve. But once the Cobb tune was installed, it amplified the turbo boost and the ST throttle was just giving too much up front. This caused the "rubber band effect" where the car would surge forward after a slight lag, and unbalancing the car, especially on exiting a tight turn.
The LT throttle allows better control but makes the car feel a bit lazy. Tbh, I didn't like the LT throttle the first time I installed it. It was only after a few spirited drives on some curvy mountain roads that I realized the LT throttle provides better control.
So the conclusion is the ST throttle is better for daily driving for the majority of drivers on normal roads due to the more eager response from the car. The clever Bmw engineers knew that.
The LT throttle map provides more control for track and spirited drives but feels lazy for daily commute. The Sprintbooster compensates for this at the touch of a button without having to flash the ST/LT maps back and forth with the Cobb AP. The best of both worlds really.
Cheers. Howie