Okay, so let me see if I have understood the major points regarding his placement--
he is six now
he was accelerated last year from Kindy to 2nd mid-year
he is in third this year(?)
he still seems to not be "topping out" of the ability groupings in his class
Is all of that correct?
If so, it sounds like the placement is still more or less working-- but maybe his boredom is due to the perception of spiraling curriculum?
Have you asked him to name some things that he's learned this year at school? Is he complaining about boredom? Or are you perceiving it? Is he the type of child who WOULD complain? Is he happy? That would probably be my first approach. That way it isn't about you when you discuss things with the teacher, it's about your DS.
Honestly, I don't think I'd be looking at homeschool given what you've posted. (As noted, unless I missed something there.) It sounds as though he has room for growth in the current placement-- that 80th percentile is actually the IDEAL from an acceleration standpoint, assuming that the basic curriculum is suitable overall. A split classroom is good, because it allows for our accelerated kids to choose social interaction with kids who are more on par with them in a developmental (chronological) sense if/when they need that, and to do academics with the brightest kids in the higher grade at the same time.
For that reason, though, that two grade split is often better when the HG child is in the younger grade.
The classroom sounds somewhat flexible; perhaps an independent project would be intrinsically more motivating to your DS if he could work on that when he was finished with his regular work?
