I haven't done it but I'd be hesitant. Think about your 6 year old in class all day (including gym and recess) with 10 year olds. And, you might consider his writing skills. Is he mature enough to sit that long? Mine is only skipped a year but because of his summer birthday, he is 23 months younger than the other kids. The teachers report a definite gap in maturity there and his handwriting is certainly not up to par. My thought would be to skip your son to 3rd and ask for subject acceleration any place he needs it. Not to be negative and I don't really have basis for this, but I think I'd look at it carefully.
