The elementary that my younger dd attended for most of her elementary schooling also used an inclusion model for special ed students and was the district designated school for "moderate needs" students. However, there was a wing of the school where there were extra classrooms that housed the GT teacher and the special ed teachers and the kids at various ends of the spectrum were pulled out into these rooms for replacement instruction in some of the subjects.
From what I saw, the kids with significant developmental delays or special needs spent a good part of the day in the pull out classes for maybe the entire language arts and/or math blocks. During the parts where they were in the std classrooms, like maybe social studies, science, etc., some of them had aides who helped as needed.
It sounds like the pull out part isn't happening in your dd's classroom and like the second teacher essentially is in the place of the aides that we saw in our dd's school. I could see this working if a few things are in place:
1) the teacher who is designated to work with the kids with acceleration needs has GT training and experience.
2) they have a plan for different curriculum or different levels of the same curriculum not just extention activities of the straight 6th grade curriculum for everyone.
3) they will also differentiate the curriculum within the groups. i.e. -- the kids who move faster than the avg GT kid can do less repetition or move through faster.
