We have ducted reverse cycle (9 vents = one in each of 4 bedrooms, 3 in main living/kitchen area and 2 in separate living room). It's zoned so we can turn rooms on/off. It costs a bucket to run so we try to limit use but our house (fully insulated walls and ceiling) is not much better than a tent thermally (lots of glass and raised up so a large underfloor space to build the heat or draughts up). In summer without air con on the house will get to 32 inside on hot days. In winter it can get down to 12 degrees inside. We are in Adelaide.
We run the air con at 25 in summer and our threshold for turning it on is if the house hits 27 inside. We don't run it overnight unless it's roasting so only a few times a year. We do have ceiling fans in the bedrooms which we use.
In winter we don't really use the ducted heating. We have a combustion heater which we use (we put the fire on if it's under 18 degrees inside) and in DDs room we have a small heater attached to a thermostat so it will come on if her room dips below 18 at night.
I'd be interested to know how using multiple separate units compares to running one big unit like we have. Our air con is quite old (about 15 years) so I'm sure if we replaced it a new one would be more efficient.