We don't have control issues. We keep the doors open if we need the room during the day for e.g. study or work. Especially in the morning when it's very cold it takes a lot of time before the heat from the living room (with the single heat pump ) has warmed the rooms. That's the time we are currently using portable heaters.
Adding a ducted solution or separate heat pumps is just not worth the money, takes too much time to pay back.