A-Body chassis bracing- stock and aftermarket- what's good?

i have some of those later braces for my 67 but i haven't installed them yet. somebody in a previous thread on this subject suggested that they were mainly for extra crunch bracing to supliment the required 5 mph bumpers of that era. its an ongoing debate whether they provide any chassis stiffening benefits.
my feelings are that at the very least they can't hurt.