Mikedobee said..
In my case the real advantage is because of the heaters. We are running 3 heaters. Each 2400 W.
3 heaters at 2400 watts each!

That's the worst form of heating you can have.
Unless you are in a rent house and will be moving out next week you should throw them away and get 3 X 3KW output inverter aircons.
They will use about 750 watts power each running flat strap and ramp down to about 250 watts each once the room is heated up.
They are very efficient at low power settings with a COP of around 4. i.e four times more heat output than energy input.
It's one of the few things in this world that you get more out of than you put in.

And your smart meter wont save you a cent.
When you get home at 7pm and the house is freezing cold in winter, you will be running the heaters at the most expensive rate.
When you all go to bed and the heaters are turned off, then the rate will come down, and you wont be getting it becaue you will be wrapped up snoring in bed.