I ordered my truck and endured the three month wait so I could get RAM Boxes on a 1500 without all the extras I wouldn't use.
I use them regularly to store all the stuff that I used to store in the cab like tie downs, hitch receivers, hand tools, etc. It keeps the cab quieter since I can't hear things rattling in the RAM Boxes (a little scrap carpet helps), and much easier eye level access compared to fishing under the seats for what I need.
It fits my chain saw and kit nicely, and keeps the fumes, chain oil, and sawdust out of the truck, without the opportunity to roll around and scratch something like it would if I just left it in the bed.
The boxes lock when I lock the truck. A determined person could pry them open with a flat bar, but I don't keep anything of extraordinary value in them.
The loss of space in the bed really wasn't usable space for what i haul, and sheets of plywood fit just fine in the bed.
Yes, the fit to the fenders is not perfect and you can see some waves in the covers if you look just right, but I mainly use my truck as a, ...... well,......truck, so it doesn't bother me much.
I would absolutely buy the RAM Box option again.