NOTE-the opinions that follow are those of my own and do not represent those of Beachbody or anything related.
So-which one is better..I'm not quite sure. Which one burns more calories...It varies from person to person, of course. Do they both make you 'workout in a puddle of your own sweat' and make you say "ma-ma," YES! One thing I do notice about these 2 workouts is that IntervalX (which is apart of the P90X+ system BTW), is that it gets going right out the gate. There is only 1, I repeat, 1 BREAK in the whole thing. And I feel that it better hits different parts of the body with the wide array of movements, and how Tony H. heats up the intervals in 3 stages; the first stage in the movement being the "starting" point for 20 seconds, then the second stage is intensified and faster, and the third being, excuse my french, balls to the wall speedy and deep. Some moves HURT (in a good way of course), and there really is just DNA flying everywhere and always that tell tale puddle of sweat beneath me.
On to INSANITY, which I got as a preview. It was a Cardio Plyo circuit, I forget the exact name of it. There are alot of breaks in the program. Like IntervalX, it gets going pretty quick, but with really basic movements for the warmup. By the end of the warm up, you are sweaty. Alot of the sweat starts pouring during the stretch that follows, because you stop suddenly with the cardio warmup. But make no mistake-Shaun T brings the heat as well. There wasn't alot of "burning" so to speak (like in alot of Tony's moves), but alot of cardiovascular, "I'm so out of breath I'm going to puke" kind of thing. I'm sure there is a HUGE calorie burn in this DVD--but not alot of 'strain that produces muscles' kind of thing. Again, I could be totally wrong, but it's just what I think. For some people-this will be perfect for, and I'm excited to see how it plays out in people's lives. I am definitely going to mix it up and get it when it comes out, but I will still be doing IntervalX as well.:)
Why the comparison, you ask? Well, I did IntervalX today, and it was just on my mind during the workout, like, "Is what I'm doing now, harder than Insanity when I did it for the first time a week ago?" At that point it would have been a big fat NO. When it was over though, I had enough time to contemplate both workouts in my head. My conclusion is that depending on where you are in your fitness journey and what you want out of it, will determine which system you get. If you are feeling frisky, get both, and try them both. I myself am incorporating it all into my fit regime, but I am a little crazy, and I incorporate ALOT of Beachbody workouts together now. Soon enough, you will probably do the same thing.