I think to really answer the question one must know the true purpose and function of heat. From my own experience from observations and studies as a biology major, heat is a form of energy. It the root difference between warm blooded and cold blooded animals. Humans are mammals which are warm blooded creatures. If a human gets a fever of 105 degrees F then they are in serious trouble. Such a slight change in temperature can be the difference between life and death for us. This is because our metabolism functions best at a particular temperature. If those temperature rise too much then it causes degredation of protein and important enzymes. So therefore humans must maintain a relatively constant body temperature to function properly.

As for cold blooded species, the majority of their body temperature comes not from metabolic activity but from the environment they live in. This is why they can tolerate such vast ranges in temperature compared to warm blooded species. So to get to the point, it is really a matter of at what temperature do ball pythons function the best. As long as there is a temperature gradient within their range then just let them control their own body temp.

This doesnt really truly answer the question, it is just my thoughts on the subject and hopefully gives the rest of you something to think about.