Those are very, very good scores. And I think what stands out to me is that the lower (though still high) scores are in English and Math - two areas that test more specific things that need to be learned. His science and reading really show overall intelligence and comprehension. I don't think it's bad to let him be child-led, but I do think that knowing his abilities, it's okay to also push a little. We met with our own ds10's 5th grade teacher, GT teacher and principal after we received his 4th grade EXPLORE scores. No one doubted he was a smart kid, but showing them concrete evidence that he could do more really helped. This year, in 5th, his regular teacher and gifted teacher have pushed him and held him to higher expectations. He's not lazy, and he's not really a perfectionist, but he is just happy to do whatever and move on to playing, or ESPN, or whatever catches his fancy. Having them say, "I know you can do better," or, "from you, I'd like to really see a longer report, and more analysis," etc helps. We don't force him by any means, but we do encourage him more and push him more. I think part of it is just age and maturity and he's grown a lot this year, but I do think it's important to let them know that they have a lot of potential and you want to see them reach it. For my own ds, he has a lot of free time because elementary here still has very little homework, so we do expect part of that to be spent in something productive - doing AoPS, learning to type, exploring science websites, writing a story, etc. We don't make it "do this because you're smart." We expect ALL of the family to engage in learning.. that's just a given. What changes because of his test scores is the level we expect, if that makes sense.
What is the curriculum like in middle school? Will it still be a pull-out GT or full-time? For our three older children, the transition to MS full-time gifted provided a lot more enrichment than our pull-out elementary, and they seemed to step up to the challenge. Congrats to him on the awesome scores!