I have to fight against second-guessing too. I think second-guessing goes with the territory of being a concerned, active parent. (Why I'm still looking online to see if I could have gotten a better deal on the car we bought last month is another story
).
Kriston and Mia, in our situation, we are lucky to have weapons to "fight" with (state law). Not a guarantee, but at least I know we have a decent shot at getting our district to teach him something. There may have been a higher risk of a losing battle in your DSs situations. Our son is also not miserable. Not learning much, but happy overall. And he's only 6 so I feel we have a couple of years of leeway before there's a real danger of full blown underachievement syndrome, KWIM? Mia, is your son happier now? Kriston, if my son was noticeably unhappy with school as yours was, I would not risk his well-being by keeping him in the situation.