Never played the Fallout stuff (I guess you are talking about Fallout?).
I am.
But its hard to say. I think that Dawnguard, NotN, and most of the FO dlc were the same size. Fallouthad 4 decent sized DLC, and one big one, broken steel. Nothing was as small as Heartfire though.
I wouldn't mind if they had a few more DG sized DLCs, but for The Elder Scrolls thereshould be at least otwo large dlcs I think. Oblivion had a lot of house DLC, some quests, NotN, and the Huge DLC of SI. I think that can easily count as two large DLCs.