The majority of cost and weight of building a bike is in the components. The China frames are so inexpensive that they are 1/4 or less of the whole price. As part of that, they are also less than 1/4 of the weight in even the lightest builds. So weigh, both literally and figuratively your goals. Moving stuff from a low end alloy bike to carbon will save maybe 3 lbs, probably only 1-2 lbs.
It all depends on your intended outcome.