It kind of sounds like 6 of one, half dozen of the other here. Both have strengths and weaknesses, but neither seems to outweigh the other in strengths. Knowing what I know about your situation, I think I would stay put and push for more differentiation. The first school is familiar to your child, he has friends there, he knows where everything is. That means something for sure. They are trying and working with you. That means a lot.
It's a difficult decision for sure!