We have a two-level, five bedroom new build in Auckland which came with a single-zone ducted system. So outputs are the bedrooms plus upstairs and downstairs lounges. The vents are tidy and unobtrusive - much less space than a wall unit in each location.
We're having major issues balancing the temperature across the different rooms as there is one thermostat.
Think setting the temperature overnight for one room with a couple plus a cat vs another room with one of the kids. Basically the wife and I are always far too hot because otherwise we're freezing all the other rooms. Or setting a reasonable temperature in the lounge makes all the rooms icy in short time.
I'm now thinking about forking out the couple of thousand to get a small heat pump installed directly into our room so we can run it separately from the rest of the house.
So if building from scratch, either look into a multi-zone system or separate heatpumps. If you can get separate systems but hidden in the walls/roof that would be the best.