Congratulations on your new car! It looks great, and I understand your concerns with warranty and ESS.
I always wanted to ask an enthusiast who is choosing a Porsche over an ESS BMW why he would be willing to get a car that is so much more difficult to over-steer safely. You obliviously get a much quicker an precise turn-in by removing all that weight from the front wheels, but I assume you wont be going much sideways anymore?
Little known facts about BMW: 1) The N54 is still in production and used in the current Z4 35i and 35is. 2) In a Z4 you can get sport+ steering combined with normal suspension etc by selecting DSC=off. (Update: DSC=off also offers sports steering in the M135i) 3) All Z4s with 19" wheels are still only offered with the worst performing OEM tires ever sold with a DCT equipped BMW (Potenza RE 050 RFT).