I agree with you. I have a 2008 750i with Dynamic drive. I purchased a 2011 535i and was very disappointed with the handling compared to the 750i.
I also thought about a retro-fit but its a mess. First your 535 uses electronic steering, no hydraulic pump, the Dynamic Drive needs one. Second you need the Dynamic Drive Control computer and all of the inputs it needs. This is major work and expensive.
So what I did was purchase After Market Sway Bars, front and rear from Eibach, about $440.00. Installation is easy, 11/2 hours. Now the 535 handles great in the corners and is even a stiffer down the straight. I highly recommend this approach; the F10/535i desperately needs it.
