We were advised to put Junckers solid down on our UFH - the only one the floor installer (a family friend, so no kickbacks etc) would recommend long-term.
Very happy with the floors. A slight shrinkage in the winter, but fills up nicely in the summer.
Brooks were the only people that stocked it, it's horrid expensive, but we bought in one of the six monthly sales (I believe there's one on at the moment).