Edit – just had a call coincidentally from the Nu heat guy. The lo pro uses 10mm pipes, raises the floor by 15mm and the pipes are laid into gypsum backing board. He also said again that approx 10% of the heat would be lost downwards.
The quote for 65 sqm was 3800 + vat.
The price for a traditional wet system, which would involve digging the floor and putting in insulation etc was 1800 + VAT.
He reckons running costs between the 2 systems would be similar, they work at the same heat, just one has more pipe work and is more responsive.