It's very easy to modify CM if you want to completely fatigue your lower body so that you have zilch energy left when you are done.
Instead of doing the 2 mins upper body compound moves with weights, grab your barbell loaded to 30 pounds or whatever you like and pump out lunges, squats, plie squats continuously for the 2 min period. Grab dumbells for other 2 mins weight periods and do lunges onto the step and lunges off the step, as seen in CTX Power Circuit and MIS. THis way, you are working the whole time, and believe me, because you are fatiguing the legs more, it gets tougher and tougher to get through that cardio! It's a real challenge, and i love it. I do this often and always in this way, whereas I do Bootcamp once a year. It may be an overall stamina challenge, but for me, the weight training is not very effective. It's endurance rather than strength.
If that's what you want, then great. But I don't see the point in working the upper body for endurance. The lower body, yes, which is why I do CM the way I do.
In the end, it all comes down to personal preference. Don't let anyone fool you into thinking that CM is easy and BC is tough. Tough is what you make it and where you find it.
Clare