My main concern would be the teacher - although I don't know the teacher (and I suspect you don't really know her either). What you're hearing might be a teacher who is convinced this isn't going to work, or it could simply be a teacher who states all the reasons that could be issues up front and then falls in love with your ds and he'll have a wonderful experience and you'll never hear another potential negative statement again. My ds has had a teacher with a personality like that - when ds wanted to try something new and challenging she will spill out all the reasons it might not work - it would sound really intimidating and negative (to me) but not to dh - he was used to her style from being in her classroom, and he listened to what she had to say, and then moved forward - it was her way of preparing him for challenges he might face, rather than intended to discourage.
When the teacher remarked that she didn't know how to give him a math grade given the crazy logistics,
I don't understand that at all, unless there are different grading systems for early elementary and 5th grade (like O/S/etc vs A/B/C)?
polarbear