I had the lane change warning on an '08 550i. It was a neat feature but not needed unless you are prone to nodding off when driving.
It worked very well. As soon as crossing either line in your lane, the wheel vibrated. I would not want a system that tries to correct your direction. This doesn't, only a warning. One side effect is forcing you to signal a lane change. If you don't do that, don't get lane change warning, or you'll just turn it off. Same if you have a habit of cutting corners on a twisty road. One thing it does is remember your setting every start. Turn it off and it will stay off.

__________________
Richard
Sir Snaps-a-lot, 9 Time Dragon Slayer (54 runs!)
2011 X5 50i Alpine White, Biege Nappa /Lt Poplar M Sport
2009 Z4 35i, Black Sapphire/Ivory-Black/Anthracite

Gone but not forgotten: '08 550i, '06 X3, '06 650i, '02 M5, '99 540i