I currently own an 06 4.4. I probably paid too much for it...but that's besides the point.

One piece of advise is to avoid the ride height adjustment option. I've owned serveral BMW's (this is my first X) but I knew something was wrong after a couple of weeks of driving it. It took a few visits to the dealer to get it fixed. It was something to do with the struts, not exactly sure what it was. It affected the tire pressure monitor, and the 4x4 light kept coming on, and there was a loud "clunk" when I hit a bump, as opposed to that solid sound I was used to hearing from a BMW.

It feels great now, and the suspension seems to be working properly but that would be a very expensive repair if you aren't under warranty.

I have 20" rims as well. Although it looks great, I probably would have settled for smaller rims. The ride is a bit rough, and I was lucky enough to get a screw in the side wall on the back tire about a month after I had it. Replacing two 315/35/20's totally sucks!

Good Luck.