There are a lot of people who make the schlep to Juilliard pre college, there are people who drive from Virginia, people who were driving from Michigan, people flying in from the west coast. Juilliard pre college is a wonderful program, don’t get me wrong, but I also would question whether you cannot get the same experience at a good music program elsewhere. NEC prep is a bit different than Juilliard pre college, from what I recall of NEC prep it is kind of a la carte, where students don’t necessarily have to take all the theory and ear training and such that is required at Juilliard pre college, though of course students can take those courses. More importantly, NEC prep has a pretty strong faculty, and kids come out of there and go to elite conservatories. You didn’t mention the instrument, I am assuming strings or piano simply because the kid started at a very young age:). I know NEC has great faculty who teach at the pre college level, and to be honest given what you have locally, I personally would think twice about going elsewhere. Juilliard pre college has some great teachers, there is no doubt, but unless you found that no one at NEC prep worked for him, to me it wouldn’t be worth the costs of going to Juilliard Pre college, the travelling and wear and tear and such.
In terms of switching teachers, it is pretty rare for students to have a teacher that can take them from the beginnings all the way through, though some students for whatever reason get into a top teacher early, but that is rare IME. Teachers have limitations, and the good ones recognize when they cannot take a student beyond a certain point. Sometimes it is because as the kid has gotten older, their visions of things have diverged, sometimes it is the teacher simply is a lot better at getting kids started (the same way that top level teachers would be bored to tears starting a kid out). And yes, it can be difficult, because the teacher probably cares, and hates to lose the kid, and some teachers might feel insulted, as if saying “you aren’t a great teacher”. Good ones IMO recognize when change is needed, and think of the student’s interest rather than their own. A friend of my son’s transferred from the school he is at, to another school, leaving a first rate teacher because a teacher he had worked with before had been hired at the other school, and felt it would work better for him. His current teacher not only didn’t get angry about it, he will still the kid at the other school from time to time, too…
In the end, you need to do what is best for your son. While I am not a big fan of all state and all region as measuring much in terms of overall ability, for reasons that have come up on here in other threads, if you feel he needs more challenge, then make the move. One thing I can tell you, as someone who knew zilch about music, when my son moved from his local teacher (who was pretty accomplished, principal member of a pretty high level orchestra) to the one he studied with through high school, it was shocking the difference, in how much his old teacher let go or didn’t pick up, it was night and day. I remember listening to all state orchestra in my state and being impressed, but then when I went to things like New York Youth Symphony, or heard the orchestras at Juilliard Pre college and other top pre college programs, I saw a startling difference I had not realized without comparison.
but if he’s been with the same instrumental teacher since he was small and he’s now in high school, he should probably move to a new teacher for the sake of his own development. Most teachers understand this, and will even prepare a student to audition for the new teacher. but it can be hard for them–they are human and get attached to students. We had an issue like this with my daughter–for years people told me she was ready for a new teacher but I was afraid to broach that subject because I knew her childhood teacher was attached to her. We waited longer than we should have and the break was not pleasant even when it was long overdue.