I love the concept of CTX, and the weight workouts are very effective, but I'd like to see more cardio variety (instead of 5 days of impact, and 4 workouts that contain high-impact step). Doing CTX 'as-is' is too much for my knees!
More variety could be included just by not combining step and kickboxing, for example, but alternating step and kickboxing days (keeping in mind what body parts one would logically work in sequence: back, chest, legs, shoulders, biceps, triceps--I put legs in the middle to not have shoulders involved 3 days in a row).
Some cardio variations that could be included (and a suggested order of their occurance in the rotation):
Interval step
Kickboxing
Low-impact step
Hi-lo floor
Boxing
Low impact floor cardio with medicine ball for intensity
Makes 6 different varieties of cardio, with a variety of impact, to choose from. (Since you only need 5 cardios to go with the upper body parts, the sixth could be included as a separate option, to be substituted for any of the others, thus increasing variety).
I'd also suggest adding on a stretch/recovery workout (with warm-up of gradually incresing ROM moves, then a long stretch, for a total of around 40 minutes). This would make CTX2 a true cross-training rotation, IMO.
