Foam panels that tubing lays into

for a concrete pour? I don't think you would want to go less insulation thickness.

Or for a dry system?

I like the Roth for dry systems

We used a similar product to the Beaver Plastics, but because of funancial and supply considerations just used it at the edges of the rooms, for holding the bends in place and inground certified sheet foam where the runs were straight, saved us some money and worked out well.