We had a '11 Montana with the "standard" jacks at the rear and now we have a MS with the level up. The level definately provides better support but it doesn't take all of the bounce out. With the Montana we used to do what Barney does, I made up a couple of tripods to go right behind the rear wheels, on the frame rails, it improved our "bounce" significantly.
What has us spoiled more than anything else with the level up system is not having to carry boards or blocks along to get the side to side level. Just push the "auto level" button and watch it do it's thing. :B
Dan