I have 2 kids there and we've really enjoyed our experience so far. I think more and more kids are staying for high school. My kids are both in middle school, but the issue for high school is the lack of extracurriculars because the school is small. There are clubs but not very many sports, and not much for kids in the arts.
That all said, I have heard the high school academics are excellent. A lot of great teachers, a lot of advanced classes, and there has been increasing involvement with UMD, which has been nice - for the middle schoolers, it's been field trips to UMD, but I think high schooler have some interaction with UMD students.
We are seriously considering staying for high school. My 8th grader is advanced in math and takes geometry with the high school. He and a bunch of kids took 8th grade science over the summer and are taking 9th grade biology this year (there are 2 sections of that class for 8th graders).