Can’t comment on Sternberg, but I attended Mogen Av and Heller, so they may have similar traits.
That said, MA / Heller is less rah-rah, exotic trips and more bein odom l’chavairo, as the mix of kids tend to be a real mixed bag. (not all kids have 2 parents at home, not all kids come from Yeshivish homes, not all kids are 3rd generation USA, ect)
I benefited from the experience, and for the right kid, its a smart move.
But one thing you will not have at Sternberg, which we had at MA, is Rabbi Sacks at Shalesh Seudos (any MA Alums out there?)