Frankly, if it were my child, I would keep her in the private school for one more year, especially if most of her classmates are staying, and you are happy with the academics for 6th grade. This way, she will do well in 6th grade, and she will need this for whatever school she does end up attending, and this will give her considerable comfort about the process. 6th grade can be pretty rough for kids. By 7th grade, things are easier for most, from what I have seen. A transfer in 7th grade seems to go better, as the kids are more mature.