At first I thought BC was harder. After doing DM 3-4 times now, though, I'm kind of thinking DM is harder. The cardio in DM doesn't get your heartrate quite as high as BC, but the cardio segments are longer (and still tough!), so that makes up for it. There are several moves on DM I have to modify (divebomber push-ups for one), whereas I don't modify anything on BC.
As an aside, I really like the shoulder emphasis in DM, because that's an area I could really improve.