I think it is important to understand that not skipping is not a benign choice. There might be good reasons not to skip, but I believe it is crucial to understand how not skipping could cause much more profound problems (crippling perfectionism, imposter syndrome, underachievement than friends driving a year earlier. (My dd will be in this situation next year and she really doesn't care--she is thriving with the skip. While I will not be thrilled for her to go to college a year early she, at 12, is already very excited about the prospect of being done with her masters and working in her chosen field sooner.) Do you know how unusual it is for the school to be suggesting a skip? I know you don't want advice to skip her, but it seems impossible to respond to this without saying that it seems unlikely her intellectual needs will be met without a skip. They might not be met even with a skip, which of course could be a reason to keep her in her current grade. Have you considered homeschooling? And are you familiar with this site: http://www.accelerationinstitute.org/

Good luck to you, I know these decisions are tough!