So, as you're seeing, homeschooling can generate strong responses. We are in a similar situation -- we homeschool because our kids are academically advanced and we finally gave up battling the schools. That fact isn't a useful conversation starter, though, for the reasons you've spotted.
So I usually say something like, 'Well, homeschool works for us for a lot of reasons, but we take it year by year, and we're very tempted by [insert local school here,] which I hear is quite good. What are your experiences?" Then you can steer the conversation in a useful direction: you can listen to that person's experiences and also learn something about your local schools. We really DO take all this a year at a time. Kids change, and it's not out of the question that dc might spend a year or more in school at some point.
That said, nothing works all the time, and I've had painful experiences in which people push ahead and interrogate me about my curriculum in depth, sometimes on the premise that I must be shortchanging dc academically. Then, no matter how gently I put it, I have to disclose that my kids are above grade level, have tested well, etc., and the interlocutor too often is offended.
I should also add, though, that I occasionally have LOVELY experiences, along the lines of, "I've known lots of homeschoolers; they're great!" or "My [insert relative here] homeschooled his kids, and they did really well!" or even, "I wish I could do that."
Good luck.
