I have a number of Rambox-related posts on the 5th Gen forum, but don't post much here. I've owned a 5th gen with Ramboxes for 10 months now, and I'm not convinced I made the right decision. I still love their sex appeal, but they come with a LOT of baggage. When you get them you are committing yourself and future owners to never being able to install 95% of devices that one typically attaches to a bed - most tonneaus, shells, racks, rail tie-downs, campers, roof-top tents, etc. The boxes themselves are weak so you really shouldn't be climbing in by stepping on the tires. There are no tie-downs on the bed rails, and none can be installed. The boxes are often misaligned, or become so. If the truck's doors are unlocked, so are the boxes, so they can only be secured by locking your cab - all the time.
I'm not saying the Ramboxes are without their charm. You still have 49" of floor for your plywood. The bed area is a very handy box shape instead of a hodge-podge of leaf-trapping curves. If you are careful you can fit a lot of odds and ends into the boxes, that are not appropriate to carry in your cab (but the cavities are some pretty bizarre shapes).
I started having regrets when I decided I really wanted a tilt-up cover for my bed. I ended up installing a Lomax tri-fold, which at least is available for Rambox-equipped trucks, but for my needs is far interior to a 1-piece.