Slab on grade perimeter insulation / Discussions

...on building a small house 35 x30 that will sit on a slab on grade. I'm planning on installing some kind of wood floor so my question is. Would it make any sense to install rigid insulation between 2x3 every 12 inches and cut down on the amount of insulation under the slab? Also, how do feel about using this 1 1/2 inch ...

...on nobody seems to be able to answer: We're building an 1100 sqft ranch on a monolithic slab w/ 2" hard foam insulation under slab (+ crushed stone & eps vapor barrier), and 2" hard foam insulation vertically around sides/edges of slab and subfloor above.  On top of the slab will be a wood subfloor web-truss system...