There are many schools that are successful at both (Lewisville and Leander ISDs come to mind). There is a balance for sure, but the process of all-region/all-state improves the individual musician. The better the individual musician, the better they will perform their music (both marching and concert).

I think it comes down to *how* you help them prepare and *what* resources you have to help them. Are you able to do weekly masterclasses/sectionals?