Well, we pulled out our son after his first semester of 9th grade (he had an IEP mind you), home educated 2nd semester 9th and all of 10th. This past fall, he went back as a Junior and the school accepted all the credits I had issued him (after much discussion with the principal). He will finish his high school career at the PS; I cannot home educate him anymore.
My daughter, who was home schooled K-8, wanted to try the PS because she was going to be playing soccer anyways. They allowed her to take German I, an upperclassman class, Biology, Algebra I, and Wellness (they operate on a block schedule). We found that the academics at our high school were sub-par (my son has an IEP so this was my first experience with mainstream academics) and I don't like the way subjects were being taught and graded. My daughter has her college picked out and some serious academic goals. After talking with her about the classes she could do here at home (and the fact that they would be a lot more challenging and competitive), she has decided to come home at the end of the semester in January and she will never go back. She will do a combination of Sonlight, Apologia, and online classes, including AP classes, through a virtual online charter school here in NH. I agree with what a previous poster said; it would be difficult to go in mid year. Meeting with the potential guidance counselor during the summer before 11th grade and discussing classes/options then would be a lot better.