I have had zero issues with the DEF systems on 2 trucks so far. There are some things about the sensors you may not know that might help you out. For example if you add a gallon of DEF fluid to an almost empty tank the computer most likely will not reset and a countdown to shut down will continue. The only way to add to the tank is to fill it up all the way to the top and then drive it until it gets the full signal. I have owned 2 of these truck now and both of them had this quirk in the system, it's not a real problem once you understand it.
If I had your truck I would keep it. You will never pull anything like a diesel pulls it.
No man has a good enough memory to be a successful liar. Abraham Lincoln
2016 36FBTS Pinnacle
2016 F350, 6.7, 4x4, DRW, long bed
B & W Companion 5th wheel Hitch