I can't answer to radiant heating... $300 for a winter utility bill sounds good to me.
I wanted to respond regarding the fireplaces. Why are you afraid of them?
We used to have wood burning fireplace (with gas ignighter) in the first house we built. We loved the fire but burning wood in the fireplace jsut made our allergies crazy and I didn't like the clean up either.
When we built this house, we opts for gas logs in the fireplace. I LOVE this option. It is warm, clean and no allergy issues due to the smoke, etc.
Hubby loves a real fire so we did the firepit outside for the real fire.
We love the gas log option. Just a thought.