I've never used either of those products, but simply wanted to suggest that by adding a joist or two every now and again, ie: 16 inch or 12 inch centres, using 3/4 " t & g plywood, gluing the ply and the joist hanger seats, with a 2" light-weight concrete topping works well for in-slab heating. (and sound-proofing)
I could see using that first product where the underside of the slab is exposed to an unheated space, but other than that, looks like a waste of money to me. IMHO.
Might want to look at pre-stressed concrete joist if you insist on using concrete for joists. Might be an option if there is a supplier available Locally.
