I have spent the past six years as a gifted teacher. I did my masters thesis on gifted ed. I have a state endorsement on gifted ed. I have presented at state conferences for the gifted. I am preparing to begin a doctoral program with an emphasis on gifted learners. I can honestly say I have never seen data which shows that gifted learners do best in heterogeneous groupings. At best, I've seen that giving them differentiation within a heterogeneous classroom is better than doing nothing.