Kirkhill's calculations demonstrate why there is no perfect solution to the protection problem. When the Isreali Defense Force introduced "Blazer" Explosive Reactive Armour (ERA), it was thought to be the best thing since sliced bread, except for the fact it needed a solid layer of armour behind it (read much more than an M-113 or LAV), and had an annoying tendency to kill accompanying Infantry when it detonated....
No matter what sort of protective system is chosen, it should be applied where it will do the most good, not just layered all over the vehicle.