I'm wet behind the ears with a lot of things, and maybe this is one of them... But I'm pretty convinced that if you slam on the brakes, the load won't go anywhere if its secured good enough...
If a load is secured properly it should not move under ANY circumstances... Be it upside down, hard braking, or rear ended.... Secure EVERYLOAD like it wants to kill you if it moves regardless of what it is!
Wanna bet? Try hauling lumber, what they call premium studs, tall units or use to be. They had a coating on them that made them slick. If you didn't know the tricks of the trade to secure them right, the center would shift out in a heartbeat. I have hauled plenty of loads in my time, and I been lucky I never lost but one, but I have had the center shift no matter how much securements I use, pipe, steel, lumber etc., don't kid yourself.
Shoulda had a few chokers with rubber mudflaps between the steel and chain for some bite. There's few things as slippery as steel on steel.
No securement is ever enough if the forces involved are greater than the strength of the system (the WLL of devices is only rated for 0.8g of forwards deceleration force). A deck driver should never slam on the brakes. It's asking for things to go wrong. Would the old "piece of dunnage" under the front and back lifts, tilting them towards the centre trick work/help? This is why I prefer dressed lumber.
If you are hauling something that you know to be difficult, wouldn't you make sure that the strength of the system, exceeds the forces involved?