There's a huge difference between Miracle and SoSac. While SoSac makes it so you still get damage, the purpose of miracle in that deck is to survive in case the opponent gets one or two creatures out that will annoy you, or that may take you near to death. The miracles are there just as safe guards and to, quite literally, gain more money when you win.
SoSac on the other hand, will need a 20 damage per turn to be profitable at all. Which, in this deck.. is just a no.