Your DD will take PSAT in High School and if she skipped too much, her PSAT score may be not as high as it should be and she may miss out on National Merit Scholarship, etc...
Possibly, but the impact of being undereducated for years could be the same. My dd, who started 9th grade shortly before her 13th bd this year, is in the top few percent of her class and has won academic competitions and awards even when compared with grade peers although some of the others with whom she is being compared are two yrs or more older.
Maybe she would do better on tests like the SAT/ACT/PSAT if older but I'm not sure. Overall, it is still better for her to be accelerated b/c it is a closer academic fit than a lower grade would be. It is a consideration, but I wouldn't choose not to accelerate b/c it might cause test scores to be a bit lower than if the child was older for grade.
