Sorry I can't help with an opinion on the new style Air Lift's. I have to old style and I just lower the air pressure to 10#, per Air Lift's recommendations, when not towing. It eases the ride and prevents the jamming you are concerned about. With regard to the porpoising, you described, if you have a 5th wheel, I don't know that air bags will help as this is generally caused by the opposite action /reaction between the trailer and the truck going over bumps at different times. Some sort of airbag pin box, like the 5th Airborne, should help.
