I did a round of Insanity Last year and tried to follow up with P90X, I just couldnt do it, Tony was just sooooo corny and the workouts were sooooooo slow and boring, especially after such a high energy workout like Insanity. If you order Insanity they have Hybrid calendars where you can do BOTH workouts for maximum benefits, that would give you the best results (IMHO). P90X just doesnt motivate me the way Insanity does, plus there's NO cardio in P90x so, like Tori said, you would still have to find a way to to do something in addition to it to burn off fat.
Allie, Insanity DOES fly by! Im glad you are loving it!!! Next months workouts will not only be harder, but they will be longer as well, but they are GREAT calorie scorchers (not just burners)!