The QX4 rides a lot more like a truck then the traditional SUV; thats why they were discontinued. With the rise of the RX300 (Lexus) and so forth, smaller/mid sized SUVs had to be more luxurious and based on car frames. The QX4 IMHO is a great suv. The problem i remember about it was that it had windshield cracking problems, but I think they were recalled for that?
When I went to Venezuela, in la Gran Sabana (basically their version of yellowstone...its where Angel Falls is) we had some (older)land cruisers and one pathfinder, and they both ate up the rough terrain. if i were taking the QX4 out there, i'd feel perfectly confident in its capabilities.