You might have to remove all references and delete the model too. Away3d might be holding on to information in that model so it wont leave memory. Away3d View3D doesn't have a proper dispose function and removeChild might not be enough for it clear the model out of Away3d. I think its known that Away3d has a memory leak in some areas. Like some of the cameras leak verts. So Away might just be holding on to itself in memory. I heard through the grapevine that the new 2.3 build of Away3d addresses a lot of these issues.
We have started to design our games to navigate through pages so that we clear the flash memory.
