Have Timberns on a '14 Ram used for a 4400lb pin horse trailer. They work great. Just mount them and forget about them. Truck rides the same when empty (it is a 1-ton truck). On the downside though, if you have a lighter load that gets them near engagement (or barely engages them), then the ride will suck... We later pulled a 24' goose with a tractor, and it rode terrible. Pulled them out (loosen two bolts, remove two bolts, and threw them in the tool box, 5min job tops) and the truck rode much better.
You can shim the Timbrens a little bit if needed.
Air bags give you a near infinite adjustment, but do cost more, and can leak, and can even be damaged on a more flexy suspension.