Absolutely agree with Hmoll. If you want maximum growth in grad school, you need the best teacher you can find. That could be at a small program or one of the major conservatories, it could be anywhere. There are great pianists in some big programs, but also brilliant people at lesser-known places. Find the teacher you want! Big-name schools look good in a bio, but other than that, people don't care where you went to school, only how well you play.