I do not know who suggested scorched heating but the did not do you any favors.
Keeping it simple think of heating like electricity.. what is a good conductor of electric is normally great for heating copper great / Air a good insulator NOT good for heating
Hydronic cast iron or standing radiators give amazing heat and hold the heat a lot longer then air.
Lots of games can be played with hot water such as non electric zone valves to fine tune the areas you want more to keep warmer /cooler.
Good luck
Under slab heating is not a great idea as you may one day decide to carpet the area or in case a pipe should fail like many "state of the art" heating systems did the home owner is up the creek trying to get someone to make good for these failures.