I added Insanity in Meso3 also - it's a surprisingly good fit, though I discovered that it is a bad plan to do Cardio Power and Resistance the day after the shoulder/biceps/tri dvd!
I'm not doing the insanity program as written. My body does best if I limit high intensity intervals no more than twice a week, balancing gentler hiking/walking with steady(er) state/longer interval cardio (like kickbox) two or three days, and a long bike ride on the weekends. That's 2 intense intervals, 1 endurance, 3-4 additional cardio sessions including hiking/walking chosen based on how I'm feeling. One at least of those hiking/walking cardio days will be an active rest day. Also, I travel quite a bit. On travel I stick with CardioCoach for my intervals, and my active rest day is 30-40 minutes walking through airport concourses with bags, up and down stairs
. So far it's worked out to do two CardioCoach during travel weeks, and do two Insanities on non-travel weeks. Roughly alternating those two this month. I'm doing my STS on an approximately eight day cycle for travel weeks, and a seven day cycle when I'm not travelling - that tiny bit of extra recovery time for travel weeks makes a huge difference. STS/strength is the focus of my program now.
Since I'm already doing interval training, I didn't need to change my diet at all - I'm eating as clean as I can under the circumstances : ) The major difference I see with Insanity versus CardioCoach and my other interval workouts is the that explosive power is more obvious and nearly every move involves the core and glutes. CardioCoach is doing more for my cardiovascular capacity and overall stamin, and ability to regulate heart rate; Insanity is doing more for my core, and ability to move fast/powerfully. I'm really liking the combination of STS/CC/Insanity - and I bet that STS Cardio will do even more! Can't wait for that
One thing, I'd suggest self monitoring for overtraining if you aren't used to intervals. In my body, it's a danger sign if my sleep becomes broken and I feel jittery, and have a higher than normal morning pulse. If that continues, I wind up in the overtraining zone and need to throw in extra active rest days. This is how I discovered that three HIIT sessions a week is more than my body likes on a regular basis, and also why I wouldn't be doing Insanity as-written even if I weren't in the midst of STS. Everyone's so different, though, and I see others who are mixing Insanity and 4DS with very nice results.