Note the two lines of research referenced regarding BFLPE are not specifically about HG+ students, and are probably better compared to the research on athletic success of students who are old for grade:
They tend to have better long-term outcomes, apparently because coaches preferentially pick them for additional opportunities for play and training, conflating their chronological-age-based physical advantages with actual differences in native ability. This becomes a self-fulfilling prophecy for moderately-above-average potential athletes. (More training means better performance means access to still better training leads to even better performance...) [Sidenote: this cycle is also one reason why our current pay-to-play youth sports system significantly disadvantages children with fewer family resources.] Exceptional athletes are less affected by this because they show such high ability that they are more frequently allowed to "play up" to the age bracket that best matches their performance and developmental needs--aka, acceleration.
