Test results are a marker of funding and focus on testing. Touring a school and talking with teachers tells you more.

Our family experience over a few generations is that a gifted kid is better off with more time/bandwidth to pursue their own interests (and find friends and maybe a mentor along those interests) vs the damage a bad or indifferent school will do, which is a lot.

That said, when our own kid got older, our top priority became finding a supportive community where she could find her people.

Advantages are one thing, but it's also important not to quash their love of learning (or of life).