Thank you all for your replies. This has been valuable .

@polarbear : The private school would entail a move eventually because of the distance. If we decide to do it , we would definitely do a try out and do the commute for a while before we actually move..

I agree that supplementing just for Math is relatively easy and we are doing it . I was looking at other things that might come with the private school - kids who are more like DS who like math and science, a diverse set of kids (The private school is actually more diverse than the public school DS is in). What are your thoughts on that ?