We've found with the AVID program at our school that it is NOT beneficial for the group to be kept together for their classes. Our AVID elective teacher did that with her first group and the result was stigmatization. The staff claimed the it wasn't a "real" pre-AP course because it was all AVID kids who weren't "real" AP kids.
After that first year, the AVID kids were not separated from the rest of the group and we all agree that it is best that way to maintain the level of rigor needed to truly prepare them for college (as is the goal).
I know this isn't what you wanted to hear, but it is food for thought.