I've recently spoken to the rep for Fineo in Scotland, and also a window manufacturer using it. Fineo is made in Belgium.

The window manufacturer makes mainly sash & case, and is the only person I have spoken to who enthuses about linseed oil paint, so is quite a traditionalist. He is about to retrofit Fineo in his own house. Of course the thin-ness of the product is ideal for this, but he also sees it as sustainable because the units can be fitted with putty and hence are easily replaced while retaining the frames. As there are no seals to perish he thought the units would be very resistant to failure, but Tony's comments make me wonder if they have any data on this.