A PTC heater is not 309% efficient that would break the laws of thermodynamics. A PTC heater is 100% efficient as all electricity in is all heat out but it can’t create more energy that you put in.
A heat pump can be between 300-500% efficient because it’s not using power to create heat it’s just moving and concentrating it as you probably know.
Totally agree about the choice that’s probably why Skoda left it as an option. Also when you the heater it’s not constantly on you often turn it down or it naturally cycles on and off. I stuck with the standard heater on the Sportline plus I just ordered I don’t think it’ll make a big enough difference. Maybe in colder climates like Norway etc but here it rarely gets proper cold for very long esp in Norfolk