Not reading every comment on here so I apologize if this has already been said -- From what research I have done, car's that have had extensive work done to the front of the car (or any part really) seriously fatigues the metal and therefore never holds up in a car accident as well. I can't remember if it was Top Gear of Fifth Gear who did a special on used cars that we're being sold where frames were re-straightened etc.

Each case is different though too. My Two Cents