I don't have my Model X yet, but based on past experience and some fairly extreme off roading with a range of vehicles from Audi's, and Subaru's to Jeeps and Land Rovers, I expect the X will be better than your average SUV. I certainly wouldn't treat it like a Jeep or Land Rover, but then I've taken my Audi Allroad, SQ5, and numerous Subaru Outbacks into all manner of rough, deeply rutted, and rocky roads without trouble. Pretty much ANY production vehicle is going to have vulnerable spots underneath, and I wouldn't think the X is any more so. Unless the vehicle has been modified for heavy off road use with heavy skid plates, you don't really want to be hitting any rocks on the undercarriage or you risk damaging all manner of systems. So, as with ANY vehicle, when you're driving into rough conditions, you should be doing your best to avoid hitting anything!
Go SUPER SLOW, when traversing an obstacle, and make sure you have adequate clearance by getting out of the vehicle and checking first. I expect the great torque and regen capabilities of the X will be very helpful in steep terrain. The vast majority of the time you don't need to clear huge rocks to get where you want to go, but sometimes it's really helpful to be able to get up or down something quite steep and/or slippery, and I think the X will do great.
So, from what I know now (and that does not yet include first hand experience driving the X in any "off road" terrain yet) I expect the Model X to be a very capable vehicle for light off road duty. As I'm sure most people would agree, I would be very aware that I'm driving an extremely expensive vehicle and be very cautious to avoid damage (there's ALWAYS a risk of damage whenever you're off road), but I think the car will perform well.
