My cousins went to an Islamic school for elementary school and then switched over to public school. One of them is now in college, two in high school, and one in junior high. They are very good, religious kids (girls and boys) but they also get along with everyone else. All of their friends are muslims. They are very friendly with kids of other religions but don't "make friends" with them.
When they first switched to public school, they hated it and had a really hard time adjusting to it. But I think most of it was because it was a new school and new people not because of the Islamic/public difference. Now they are all really happy and well-adjusted in school.
I've seen a lot of kids in my community go through Islamic school and then public school. They don't have a one-track mind. They're all very ambitious and seem to know exactly what they want in life. I think Islamic schools tend to impress the idea of a good, respectable career a lot more than public schools do.. where they concentrate more on exploring all the creative sides. (Now it's up to the parents to determine which they think is better for their child, since every kid is different) All of these kids are social and involved in the community so there doesn't seem to be any communication issues.
From my experience, I think it's a good idea to have kids go through Islamic school at the elementary level and then switch to a public school. That way they get a good Islamic base but aren't blind to the fact that there are other kinds of people in the world.