UFH and laminate flooring vs semi solid

m_stan

I'm installing underfloor heating at the moment and had intended to put down a high quality laminate floor on the first floor. Since the house is a renovation project and I wanted to avoid the need to reinforce joists across the whole 1st floor to support a screed solution, we've gone with a screedles job which involves a layer of 12mm plywood, then wooden batons with 30mm foil backed insulation boards with grooves for the UFH pipes in between. The idea is that we'll floor directly on top of this.

Laminate is the best solution in terms of wear (kids bedrooms etc) and cost. However my builder is concerned that the laminate floor will be less likely to transfer heat than the semi solid, which is obviously more likely to wear and much more expensive.

My questions are:
1). Can I put a 9mm laminate floor down straight on top of my batons if they are close enough together? If so what should the baton width be? If not what depth of plywood do I need on top of the batons to support the 9mm laminate and does this compromise the heat transfer from the UFH?
2). Does laminate flooring generally transfer heat less effectively than semi solid in anyones experience?

Interested to hear from direct experience. Thx

m_stan

*bump*