If the house is not being renovated, and the walls are closed, and you don't want dust and broken walls, Ductless mini Splits are the way to go. However, its a lot of work to flare the ends and make sure there are no leaks. Run the copper and condensation lines neatly and with kinking them. It takes about a day to install one unit and sometimes more. We go through brick walls, plaster walls, roofs and floors to run the piping. The condensation pipes need to be pitched properly and sometimes even need a pump to properly install the unit. Running ductwork requests two people, which is no different than installing a ductless split.