The radiant heaters will eventually heat the room, too. they just heat you before heating the air like a convection heater.
Think of it this way - if a radiant heater is outputting a kilowatt, but there's no person in the room, the energy goes somewhere - eventually it may be that objects are unevenly heated if they receive the radiant energy but as they get warmed, the air around them will be warmed, too.
As far as the costs go, I wonder if:
1) the 120 target isn't a little idealistic
2) if it includes respondents heating less square footage than you are. Not as a matter of building size, but as a matter of not heating the entire house to comfortable
You may be hoping to achieve efficiency that isn't efficiency, but rather lower average house temp when including unheated areas. Or that isn't properly compiled or expressed by the system.
I've always been stingy on heat and air. Last year, our A/C is finally running out of charge on an outdated refrigerant. One month, our A/C bill (hotter than normal, too) reached $250 above normal electrical consumption. This as a month with a lot of 90s F and I have a spouse who is unbending and who also decided it should be colder than normal.
this spring, I will replace the A/C with something more efficient as it's 40 years old now, but when I polled neighbors with similar size cooled area (2000SF cooled), they returned figures a lot more like my "bad year" than typical.