I understand that the ducted systems are less efficient, but the ability to better control filtration, outdoor mixing and humidity makes up for that.
But they're not less efficient, ducted systems are more efficient. Mini-splits multiply your refrigerant lines, compressors, heat exchanger, condensing coils, etc., so you're multiplying your inefficiencies. A single variable rate, zoned, ducted heat pump is the most efficient, but they definitely cost more.