Mostly issues with build quality. The RX, as you know is just a modified Camry platform and drive train. It looks like a team of trained monkeys designed the undercarriage. Placement of the front strut towers indicated the car had no off road performance given in the design. Although car sat on a higher suspension, the breaks and suspension were not designed to deal with the loads, and extra weight. Individual components were better quality in the MB by a long shot. For Lexus it was out of sight out of mind. We also got to take both through performance and traction test. The RX was a joke. The AWD system is anything but, and the traction system, at the time, was little more than a limited slip.
The option list on the GL is costing us sales. As great as the GL is doing, the market will slow down. I've lost multiple sales because of supply issues and the long option list.