I have the top of the line ARE Z- series on a 2011 duramax. I have had to replace the lock/latch (under warranty) and have small but persistent troubles with water intrusion around the seals of the back glass. I also have a horrendous dust intrusion problem, but that's the fault of the bed design, with large open spaces that lead to the wheel wells. I taped it all up with gorilla tape and installed a tailgate seal and that helped a bunch, but 3 years later the tape needs to be redone. The cap looks great, but the water issue is aggravating.
