Hi Nightshade-
Your son sounds a lot like my daughter Olivia... only child, extremely bright. When she was little I was lucky enough to be able to barter graphic design for tuition at a VERY good ($$$, creative, small) preschool for her, where she thrived. When she was 4-turning-5, she was absolutely ready to go to Kindergarten. I WISHED I could send her to one of the really progressive, creative, private schools we have here, but there was not way we could afford it.
I was nervous about sending her to the local public school. I didn't want her to slip between the cracks and not be challenged. This is a kid who was reading Harry Potter by herself at age 4!!! We never watched TV other than a few select PBS shows and carefully-selected DVDs. I was nervous, but we decided we'd at least give it a try and see how it went.
We were really lucky and her Kindergarten teacher was an absolute gem. She really nurtured Olivia's talents and intellect, going so far as to set up a gifted-and-talented class for her (they normally didn't begin that till like 2nd grade) and sending her to read with a 1st grade class. So we kept her in the public school until 3rd grade (more later on that); and only one year did she have a teacher who didn't really spend extra time on her. Even so, the school was already set up with a great gifted and talented teacher and was sending her to read a grade ahead, so it was OK. Of course, at home she would read like crazy and do all sorts of cool science and art projects on her own.
I was really glad that it worked out so well, since she had very few opportunities otherwise to play with kids her own age and I think it was really important for her to have the social interactions.
In grades 3 & 4 we lived on our sailboat and home-schooled. I am so glad we did this for many, many reasons. Anyway she came back way ahead of her peers and was put into G&T classes for both math and reading when she re-entered 5th grade at the public school.
She's in 6th now and still in public. we recently had our 1st parent-teacher conference and the teachers are completely impressed with her poise, intellect, willingness to participate and share opinions, etc. The ONLY thing they mentioned that they were at all concerned about is that Olivia is a bit of a loner, and not all buddy-buddy with anyone and less concerned about the inevitable middle-school social scene than her peers. WE talked about it with Olivia, since I was worreied she's unhappy about that.... but she's not. She's totally happy with her social scene, so I guess its not a problem. I do think that being an only child and HS for 2 years contributed to her "loner-ness" though. Although it also probably has to do with the fact that we are COMPLETELY out of touch with pop culture (we now have NO T.V. at all (just DVDs) so perhaps she's just not in on all the popular stuff like kids who watch TV all the time. (By the way it was her choice not to have TV!) But, HS-wise and living on the boat, he really had to learn to entertain herself, and is great around adults, too. But, yes, I do worry a little about this and hope I haven't damaged her socially. I think not, but a mother worries.....
We ARE planning to HS again. We hope to go on a 4-5 year sailing trip in a year and a half, so that would mean HS for grades 8-11 or even through 12. WE'd stop and put her in school for a few months in New Zealand and Australia, so she'd have SOME social interaction and actual classroom experience at a High School level.
Also, regarding getting into college. I called the admissions office at Harvard (just randomly, to see what "top schools" think) and talked to her about homeschool applicants. She said Harvard gets tons of them and they are absolutely not looked down on, in fact, harvard thinks that HS kids are extremely bright in general and accepts lots of them. She said that at Harvard, at least, it was in no way putting her a t a disadvantage.
So that's my experience with HS and public schools. I think your thought about trying the public school and seeing how it goes is the right plan. It worked for us. Perhaps do a combination as we did, for the best of both worlds.
I applaud you for caring so much about your son's education and happiness. Way to go, mom!
Stacey