Hi. I'm not from WA, but I have a couple of thoughts on the issue...
Which high school is your daughter most likely to attend? If she's apt to be at a public high in Kent, it might be good to have her start to socialize with some of the area kids, as they're apt to be her classmates later on, too. On the other hand, if you see her attending a private high school, then it may not be a particular benefit to uproot her now.

I personally think that K-8 schools are advantageous as far as reducing the "middle school drama and cliques," because the kids have grown up knowing one another and their teachers also know "who's who," and who to keep an eye on. Unfortunately, in most public middle schools, if kids only attend 7th & 8th grade, there is more "jockeying" for status and position (See the book "Queenbees and Wanna be's") and teachers are getting to know the students just when the kids are trying to know each other.

Since you say your daughter is a good student, I would value her opinion in this decision. How does she feel about making a switch now?