Don't know how many people have pulled the hand brake on whilst in motion on a modern car like a vt/xy/z? I have and at speed, it is either off or on (rears locked) and unless the button is still depressed those babies are staying locked. From my understanding of the push button from this thread whilst yes the button location may not be in the ideal location it is not going to lock the rears at speed like a cable brake will do.
To me = safer