In reply to johnlc:
If you can find someone to buy used down then you can try to sell it. Alternatively there are companies which will refurbish down gear so you can continue to use it, and some will allow you to donate old sleeping bags etc so they can be refurbished and passed on to youth groups.
This seems like a good way to recyle down which might otherwise end up in landfill. This is how recycling works - materials have to be recovered, processed and turned back into raw materials for new stuff, and it is the end-use value which pays for that. It's no different from old drinks cans being recycled for aluminium, or plastic bottles being turned into fleece, or old cardboard boxes being turned into new cardboard boxes. The only difference here is that Rab are arranging the collection and delivery to the processor themselves, rather than it being done by someone like Veolia.
The only drawback seems to be that you have to deliver it to Rab's HQ, the location of which is not easily found from their website. Maybe they could install collection points at some climbing walls or gear retailers?