No experience with dump trailers or hoppers. We dump the air on the straight trucks when dumping. However we are not always on 100% level areas. We only do it for the stability and safety reason. When you get the box up on some uneasy ground or with a breeze you definatley feel the difference with the air in versus out. Even installed individual dumps (dual levelers) so that when leaning hard on on a side hill you could drop the one side when chopping. We drop the air for hooking/unhooking. This avoids some potential for "high hooks" when swapping tractors. The T600 rides lower than the Freightshaker. Also keeps people from ramming the pins as hard.