My eldest did a double-skip. He was also at a very small school, and for the most part, everything worked out very well. Based on our experience, when the school is very small, it's a bit easier for a much younger child to fit in with everyone else. I expect it has to do with feeling less peer pressure.
Unfortunately, the school no longer exists.
We sent him to a charter school last year and it was a disaster. He learned next to nothing and was unhappy socially. I think that the age difference becomes much more significant when the other kids are adolescents and your child isn't. This was definitely a real challenge last year at the larger school. It may not be such an issue at a smaller school. It wasn't a big deal when my son was a ten-year-old seventh grader in a class of five or six kids, but was an issue when he was an 11-year-old 8th grader in a class of 80 kids.
My advice is to think about different things and try to weigh them to help guide you. For example, does your son want another skip? Mine did. What about the stability of the current school? Has it been around for a while? Does it look like it will be around for a while? Can he go through 12th grade there? If not, I advise thinking seriously about where you'll send him for high school. Moving from a small school to a big one is tough. Doing that when some of the students are 6 years older than you...well, that's really tough. Academics are important, but so is being able to fit in, and when physiological changes are well underway in some kids but not at all in yours, there are emotional gaps that simply can't be bridged. Again, in a small school, this can be less of an issue. In a big school, it's huge.
I'm not too worried about DS finishing high school when he's 16. He won't have to go to college right away and there are many great things he could do with a free year or two. YMMV.
I understand that the idea of a second skip seems weird. It seemed very weird to us when we were thinking about it back then. You've just become used to the idea of one skip, when you realize that another one might be in order. When it's no longer an abstract idea, it can be hard to get your head around it.
HTH.
