Traditional Field Fabricated Gooseneck Assemblies share the same deficiencies. All suffer from a lack of a back-draft damper unless they use an inline butterfly damper which in a vertical orientation adds a tremendous amount of static pressure. With dryers an inline damper is against the International Mechanical Code (IMC). Alternatively, you can use a side wall cap which looks awkward. The several components that make up a field fabricated assembly all must be fastened together which adds penetrative fasteners which is also not allowed in dryer assemblies per the IMC. The many joints created in the field fabricated assembly all must be sealed from weather intrusion and is always a weather dependent process. Caulks and mastics have a limited life span and will need to be reapplied long before the roof needs to be redone, but long after your HVAC warranty has expired. Exposed galvanized duct is unprotected and will rust and deteriorate over time. Architectural details that specify insulation or adhesive weatherproofing jackets are expensive, extraordinarily time consuming, weather dependent and difficult to make look workmen like. Finally, they all require destructive methods to remove the gooseneck vents for cleaning and service of the equipment.