Lower an X5

[Foxx]

What's the overall opinion of lowering X5's? I have '09 xDrive 4.8 and I'm seriously considering taking her 1.5-2.0 inches lower, but my dealer said it's a bad idea with X5s, they are meant to stay the way they are, the suspension is very sensitive on those cars (supposedly). I'm not sure if I believe this, I'm under the impression u can easily lower any car, as long u use good shocks, struts and even coilovers, they would be better than the factory ones, right?
I want it just a little lower, I don't really like that high SUV look, esp having a 911 and E46 lowered to a point I can't go down into my garage. I don't want the car to become too stiff though, this one is already pretty stiff as it is, wouldn't want it to be more. Any recommendations out there? maybe an adjustable suspension? anyone?
Also, would my warranty be voided if changed suspensions?
Thanks all.