Duct material, replacement or encapsulation?

Hoping to get some advice from the pros. We have a 1 story home (under 1600 sq. feet) built in 1990, with original ducts (basement ceiling) and heat pump. The system is still working fine, but we are looking into replacement due to age and energy consumption. Most of the ducts are uncoated ductboard (hot rolled). We don't have an obvious problem with dampness or mold, but there is intermittent odor. We are trying to decide whether to have the ductboard encapsulated, replace the ductboard with new, or bite the bullet and get sheet metal. I'd prefer not to sell my newborn son... Any advice appreciated!