I knew more homeschoolers growing up than I did public schoolers, and each side seemed to think the other got a worse education. As far as I could tell there was just more variance within homeschoolers. A lot of parents homeschooled their kinds because they wanted to do a better job than the schools, so there was a bit of self selection for over achievers. At the same time there were parents who only chose homeschooling for religious reasons, and the kids ended up getting away with barely the equivalent of a high-school education. The latter seems to be the reason most pro public school people think of, when in my anecdotal experience the former seemed a bit more common, with the most common being both reasons.

At uni it seemed to me that both methods of schooling were perfectly capable of producing good engineers. Though I had one or two experiences where a smart friend who went to public school, asked me questions about homeschooling, thinking ahead for their own children, as they had recognized the public schools had not allowed them to realize their full potential.