The best person to ask about the math class would be your current math teacher who should be familiar with your aptitudes as well as the coursework demands for next year. FWIW Statistics is considered one of the less rigorous APs. IMO your ability to handle the faster pace of a combined class (along with your other classes and ECs) should be the deciding factor.
Work with your guidance counselor and teachers to create an overall schedule that will be challenging but not overwhelming.