First of all, I'm gonna make clear that my native language is Spanish, so I'm still learning english and you'll see something that doesn't fit at all in the message.
My case is HoH and public school!
The positive things about mainstream schools/highschools are that you "grow up" on the hearing world, so you can see how hearing people do interact, interact with them and etc.. I guess(?). Everyone is so different
Other things are the education that you get, as DeafDucky said, you get a really good education, but I'm going to say that there's an exception for me. You probably get the education, but if you don't pay attention when someone is explaining something or you can't hear or X, then you won't get it, so what I mean to say here is my experience, there are people who told me "How can you don't know this or X" is so basic or something like that, and I just didn't hear it in the moment or didn't pay attention because I wasn't hearing good to the person who was explaining or etc...
I don't know if I made it clear.
The social part is like 10/90.
In my primary education, I was sooooooo lucky to have classmates who were so good with me, respectful and they did let me integrate in the group. That kinda surprises me, but I guess the teacher at the moment did help me a lot and my mom of course.
But when I went to highschool (12years old) things went go really bad, on social part and the studies part too... The people with who I went on school weren't the same of the highschool.
I still do not regret going to a mainstream school, because I've developed things that I couldn't do if I didn't go.