Anytime our kids come into the discussion it get serious, but at least we see how people really feel huh?
It's tough to tell you what type of shoes are best for your child, but based on your analysis I agree the flats or barefoot are best. I'm currently in a Mexico 66 and I absolutely love it. It feels like a karate shoe almost because it fits like a slipper. There is a very thin midsole, such that the bio-feedback on impact is still excellent. In regards to the barefoot running, my views have shifted slightly. I used to think it was the greatest and should only really be done on trails and grass. Now, I think it's the greatest for any surface. I question whether barefoot advocates here have ever given pavement a chance, it's actually great stuff for fast training. Great because the stuff is practically spotless and extremely smooth, unlike trails around my parts that I'm much more likely to step on a nasty rock and hurt my foot. Glass is the usual propaganda being pushed by the paranoid, but I can assure you it'd have to be some serious glass to do real damage. I've stepped on tons of glass and it never punctures my foot, the feedback is so quick when barefoot all pressure is immediately taken off the foot. This of course doesn't mean it couldn't happen, but for it to happen to me I think it'd have to be a large and especially sharp piece and attack me at night when I couldn't see what was on the ground.
Eastbay has the Mexico 66's for about 60-70 bucks in a variety of colors. They aren't listed under running shoes, look them up by doing a search for "Onitsuka"