Ultramarina, I would not make your DD repeat CC8 based on relative weakness in the Algebra sections, especially if she is strong in the Pre-algebra and Geometry sections. It is very likely that 2nd time around, when she takes Algebra I next year, that the material will be more accessible to her.
I observed DD's Pre-Algebra class and DS's Geometry class last year and have maintained a dialogue with DD regarding her Algebra class this year as well. At our school, the GT classes are over-inclusive, which may be skewing the results. Anyhow, it seems that about 1/3 of the kids really get the materials and can be going faster/deeper, about 1/3 of the kids are getting the materials with effort, and about 1/3 are struggling and probably shouldn't be in those classes. Those kids in the 3rd category either repeat the course the following year or get lots of extra individual or small group tutoring help (in school or privately) to improve their performance. Some kids also do migrate from one category to the next based on the particular topics. In your DD's case, it appears that she is mostly in the first category and sometimes in the second. That is actually not a bad place to be as it can be excruciatingly slow when you are consistently in the first category. Just my two cents.
