hi ksfrogman, after trying 3 knobs on the e90, i felt that i was not a fan of the chrome leather stock. the m short shift was rough with the perforated leather and was a bit too chunky for my liking. one also tended to palmar flex the wrist during shifting. it would have been better , if the centre console was higher, to appreciate a short shift.
Z4 coupe/roadster's m illuminated knob is less chunky, has smooth leather and has the right height to allow 2 finger/digit shifting without having to flex the wrist- when resting on the arm rest. absolutely fab!
you can pm me anytime, if interested.