Let me get on my soap box about the fact that no matter what the efficiency of the equipment may claim to be, it is only as good as the duct system attached to it.

The majority of duct systems today consist of long (Flex) runs. This insulated vinyl corrugated duct designed to accommodate air flow actually has a high resistance to air flow. Multiple flex runs of long length in any duct system is like choking your HVAC system of air. The end result is the air handler is working longer and harder to achieve comfort. There is the other issue of having any galvanized metal duct insulated on the inside. Why take chances!