My z-series cap is fantastic, had it a couple of years. Only issue I had was it was a couple of months after I purchased it, the first time I opened the passenger side tilt window, it shattered. Good thing it has a screen behind it, my dogs were in the truck. Sounded like a shotgun blast. Must have been something stuck in the hinge that caused the glass to flex & break. My dealer and A.R.E helped me out with the replacement, not free, but reasonable.
Just moved the cap from my '11 to my '14 sport this past weekend. Fits great, and the paint shows no sign of sun fading.
If you order the roof racks, you may notice the small protective caps that they give you when you don't have the cross members on, well they disappear over time. Not a big deal, they serve no real purpose.
Lastly, get the fold down front window. If not, you won't be able to clean the rear glass on the cap or the front of the cap.
With the sliding rear window, the pups can still come up to say hi.
"Hey.... where's my donut...?"