Monolythic or Multiple Pours for Slab on Grade

Pouring a slab on grade foundation for a new addition. Here's the diminsions:
Footings: 12"wide x 8" high x 78' long
Stem Wall: 6"wide x 22"high x 78' long
Slab: 28'long x 25'wide x 4" high

City allows for two basic designs: One a monolythic pour and the other a two pour (one for the footings stem wall and one for the actual slab). The biggest difference seems to be the allowance of the two pour system to have a ridged insulating material on the inside of the stem wall. The single pour would undoubtedly be less expensive. Question is: Is the multiple pour method significantly better than the mono pour method?

 

Undoubtedly less expensive? Maybe just pennies. Might even be more since you will lose the second use of the inside forms.

The single floor will give you a colder floor. You did not say where you live, but the extra heat would count up.

What does a contractor say about the price difference - he knows the costs.

Dick