Tried goose fat one year when one of the telly chefs was pushing it.
Underwhelmed - the spuds tasted about the same to me, although in those days I would have had a few glasses of Bristol Cream on board before eating them so tastebuds may have been dulled.
The goose fat cost a few quid in a tin, so the only time I would use it again was if I was having goose, giving me ready access to the fat.