When I bought our Class C, I got levelers installed before taking delivery. I had traveled with a family member once where they had planks to assist with leveling, and I, being the lazy type, decided I didn't want to deal with all that.
These are the Bigfoot automatic. Nice.
I've tested the rig at several locations. Rig doesn't move much at all with the levelers engaged. If you are in the bedroom, you can feel some wiggling when you move. I am guessing that this is because the rear jacks are just aft of the rear wheels, so forward of the majority of the bedroom space, so we have added a quarter ton of weight the the space aft of the jacks. But in the bedroom, movement is almost imperceptible when someone up from moves around, and the same when you are upfront while someone is in the bedroom moving.
We have found that just leveling, without taking the wheels off the ground makes the most stable positioning. If I raise it enough that the rear wheels are basically off the ground, stability is lowered.
Next step is to find a location where some extreme leveling is needed, and see how that turns out. The one thing I have found is that the Auto-leveling function has usually proved worthless. It always wants to raise the front too far, and the fails to properly level the front to back correctly.