Well actually Circuit Max is, IMO, a lot harder than Cardio and Weights, so if all you have is C&W, then by all means sub, because they are both circuits. Just give your all to the cardio and go heavy on the weights.
Otherwise you might consider something more along the lines of Step, Jump, and Pump, or Body Max. Both of which are circuits with a similar format. Extended pure cardio sections at the beginning, cardio and weight circuits, followed abs. Body Max has some more upper body weight work that you could do or not do depending on your schedule.
HTH,
Matteaa