I did 40/20 this morning; after 30/30 and cardio core circuit I was very afraid of this workout, especially since Cathe ranked it as the toughest of the workouts. Surprisingly, I found that CCC and 30/30 were tougher for me. I think 30/30 was harder because it was the first HIIT workout I did and it didn't have those 1 minute breaks. They helped me a LOT. And CCC, well this one is my toughest I think. Though I have only done each of them one time through. (I just got my STS shock cardio set on Thursday Jan. 7). But all that being said, I saw my HR go up to 202 on 40/20 - I burned 460 calories for this workout. For CCC I burned 855 (these are according to my HRM).
The only other workout I have done from this set is MMA - boxing and I loved that, too. I am soo soo sooo ooooooo happy I pre-ordered this set! It totally rocks!