I am having a house built by a contractor. I will be completing multiple parts of the house myself. In my present house I placed a floating engineered wood floor over a foam pad. This acted as a pad, insulator and vapor barrier. I Have been happy with this. In the new house I am considering another engineered floor that comes with what looks like

Baltic Birch base and abour 3/8′ of hardwood laminated on top. The strips come in 3, 4, and 5 inch widths wich will look very nice. The manufacturer however recommends glueing this directly to the slab. They say it works fine even in New Orleans. I am worried about moisture and wood changes with the only vapor barrier being under the slab. Any comments or suggestions regarding gluing an engineered hardwood floor directly to a slab (Northern CA) would be appreciated.
Thanks Paul2