I've recently seen a wide variety of magnums and jeroboams for sale here in the NYC area, particularly those filled with Holiday beer. These used to be fairly difficult to find but I've manage to try a few over the years (Chimay, Duvel, Rodenbach, Anchor, Victory). All were pretty delicious but I didn't find a noticably different flavor vs their smaller siblings in 12oz or 750ml bottles. All I noticed was a much higher price per ml.
Is there an extra cost added for the luxury of having an enormous beer or can you actually taste a difference?