Here is a another thread which discussed a similar issue:
http://giftedissues.davidsongifted..../all/Advice_on_Grade_Acceleration_P.html

Every once in a while, there may be a post in which someone looks back and wishes they may have skipped a grade. Thinking about looking back provides a different perspective from which to consider decisions. http://giftedissues.davidsongifted....t_would_you_do_different.html#Post141710