Ask if there is anywhere that this program has increased math scores. If they say yes, ask for the documentation. There is no balance in the curriculum. Some individual teachers, usually one's who've been around a while, will use old materials to teach basic skills. I'm going to ask for some evidence of teacher competence in math.
Students seem to really be understanding the concepts.
If they understand the concepts so well, how come they score so poorly on standardized tests. That's because they don't understand the concepts. This is totally false. Good luck and let us know what happens.