Thought I would chime in.

I have a 2009 X5 4.8 on 20" 2-Piece Forged Wheels (not stock, much lighter wheels) with pretty decent sidewalls.

I have the H&R 1.2" Kit.

It is unbearable.. I have a 50lb tool bag in my trunk and it gets about 1-2ft of air on the slightest bump. My neck is sore, I've actually got air myself many times.

I'm having it removed this Friday. I'm not sure if its the wheels or what but its pretty bad.

The shop I'm bringing it to (Sonic MS) says that they can lower the car a little with the GT1 tool and remove the links. Sort of like a happy medium.