DS does his high school part first thing in the morning. Then he goes back to middle school for the rest of the day. The only HS students he has interaction with are those in his honors class. They sometimes work in groups and correct homework for each other. They actually like listening to his ideas when working in groups and accept him just as their regular classmate. But this really is not enough social interaction at HS for me to give you an accurate take. I think taking the classes with high school students will be just fine for your DD when the time comes, especially for STEM classes. (OTOH I even requested the MS to excuse DS for health classes).
