I agree that the self image issues could be hard in the same school if she decelerates. However, placing a child inappropriately solely to make her feel better about where she is placed can't be the right thing to do.
I'd think, like you and others have said, the first order of business would be to figure out where she actually falls in relation to the rest of her grade mates. Being below avg in her current grade can't be a good thing if that is the case. I'd expect that something should be done other than just waiting for her to improve on her own if she is struggling. That may or may not be deceleration. Maybe they offer tutoring or more individual work.
You said that Dr. Ruf tested her when she was 6. Did she do IQ and achievement or just IQ? If her IQ is solidly in the HG range and she isn't performing on par, perhaps it just isn't the right time like others have said or maybe you have a 2E issue going on like you've considered.
Do you have an option of changing schools if you have her stay in her current grade for another year?
