No, the weight of the engine is on the crank case. That is what the middle beam is for. It should be slightly taller than the side support, which is there if the engine starts to lean.
+1 on not removing the bumper and checking and re-checking that EVERYTHING is disconnected, and taking your time on the engine lowering.
I get clearance from the rear valence by lowering the FRONT of the car, and the rear magically rises up. No need to even remove the valance.
Another thread: happy reading.
http://forums.pelicanparts.com/porsche-911-technical-forum/530236-dropping-motor-question.html