Very few of us will ever be close to flipping one of our replcas. However, almost all of us will have the occassional panic stop. Many times we unintentionally cause them just be being where we are in our cars. Remember that time when that other driver's jaw dropped as he looked at your car, and he completely forgot that he was driving through an intersection with other traffic around?
Your circumstances will vary, but our cars do have the ability to render other drivers dumb, both literally and figuratively. In those cases, I want the best brakes I can get. For my $$, that's 4 x discs.