Quote Originally Posted by Kietsu View Post
Diamond Dust is a guaranteed token for clearing the duty. Presumably you'd get an Expanse Totem for clearing Bismarck EX with an undersized party for the same reason.
I had a very successful Garuda farm party a few nights after Heavensward launched, and despite running a good twenty plus times not a single feather dropped for anyone. (We did get a pony for everyone, at least!)

Cards seem to be tied to a different loot system, as they're the only thing you'll see 'drop' in an undersized dungeon or primal.
You can't undersize with HW content as far as I've seen.