I've got the Calton vault for flying with my D-28 but use the Fort case most of the time. It weighs a few ounces more than a gig bag and is amazingly protective. (Don't think I'd entrust it to the airlines luggage gorillas, though.)

So far I've found two drawbacks to the Fort. First, the Velcro closures wear out and fixing them is a pain. Secondly, the case doesn't seal well enough to be really water resistant - especially when the Velcro is weak.

On the positive side, the Fort is wonderfully designed. The handle is partly on each half of the case. You can lift it safely without sealing up the closures. The guitar can't fall out because holding the handle keeps the top closed automatically. Sure wish they made 'em in other than dreadnaught size.