Oh wow, I'm so glad I'm not the only one!
I was HS all the way, and DH and I planned that for our kids too...but then life happened and DS1 was 6 before DS2 arrived...DS1 was clearly a social butterfly and was just lonely being home on his own, even when I took him to weekly playgroups, swimming lessons, etc. So at 6 we put him in half-day kindergarten at a charter school. It was a GREAT experience.
Then we had to move for DH's job. Now we live in a teeny weeny town--there are 7 elementary students (yes, that's K-6). They are together in one classroom--sounded great to us! Unfortunately, it has not been so great...
(warning, this is going to turn into a rant!)
His teacher (to put it gently) is a moron. At 2nd grade, DS is one of the older kids in the class (1 K, 3 1st graders, then DS, then 2 older kids who work really independently). He is gifted (he's been tested), and he is clearly not sufficiently stimulated in class. He's been having behavior problems because he's
bored, but the teacher thinks it's because he has issues and she wants to keep him in 2nd rather than moving him to 3rd (we bumped to 2nd instead of 1st this year because he was clearly under-stimulated). Anyway, we pretty much told her no way, he will bein 3rd grade. We have been working to stimulate him at home--he's doing multiplication over the lunch table and things like that.
I've thought about pulling him out to HS, but if we do he will be more bored and lonely than ever--there is NO extracurricular opportunity in this town. It's an Alaskan fishing villiage of 60 people. Yes, 6-0.
Here's the real kicker--his teacher, the inept moronic teacher (who couldnt' pass her praxis--the basic "are-we-competent" teacher test required for renewing her teachers certificate): That woman is DH's boss. Yeah, DH is the secondary teacher here, and she is the superintendent and elementary teacher. SO, we can't exactly say anything to anybody because in a town this size, NOTHING is anonymous, and saying something would likely jeopardize DH's job.
We plan to move next year, but right now they have offered DH a grant that is paying for him to get his Masters degree online, and that will boost his pay and we really need it, so we're committed to stay for that. So we have to slog through another year of her...
I considered writing to the school board about her ineptitude...but I think we are the only dissatisfied parents in the town, plus she'd take it personally, and like I said, nothing is anonymous here...
I am seriously considering pulling him out for half days and having him go the other half--DH isn't sure about that, but I think it would allow DS his social time, but also have him with me to get properly stimulated. After all, this woman is clearly not qualified to teach my gifted kid, you know?

/rant.