Yes...I own an ML and go off-roading.
While it's not rockcrawling...it is off-roading.
I do agree that the vast majority of ML owners and other so called SUV's/4x4's never have and never will take their truck off-road. Not to mention, the vehicles are not very capable.
While my ML does not have great articulation, with larger tires I have over 11 inches of clearance, which is more than LR Discovery's. The ML has low range and active locking differentials. Not true lockers, but it's the same thing in Land Rovers and Range Rovers. So it can't be too bad.
It's not the best rig, but it's not the worst.
check out pics...
www.deckowski.com