Hi
Yes it's a good idea to have the A pumps when the personnel have moved out and the ground crew has shown you the red flag for the pin, we have had SYS A going up with the pin in during a push but we saved the tow-bar by pushing straight.
I guess the SAA procedures for push back are great, nothing you do until you see the engineer left or right of the aircraft and all ground equipment removed.
Zenj