I have 2011 550xi, no hesitation issue at all.
For the 535, some bloggers claimed the tranny is learning the driver's input at the first 1000km or so (adaptive drive), since you are not supposed to floor the car during the break in period, thus the tranny may be thinking/learning your accerlation charactistics. Maybe a myth or simply software issue ... nobody knows.
Here is the latest on the software fix ....
http://www.bimmerfest.com/forums/sho...d.php?t=580245
SIB 12 09 11 You have to be specific about what the problem is so the SA will write the RO correctly. When the tech reads it he will search and find the SIB.
Problem: Delayed throttle response when driving off.