Well, Tom, I really don't know the answer to that question. I suspect that no matter the GI of a meal, that glucose is going to hit the blood stream eventually, cause an insulin response, and get driven into fat cells. That's just my guess, though. As for the B-12, you're probably right. The other points, though, seem to be good enough reasons for me not to eat grains.
As for the people in Hawaii and their rice, they might be healthier with brown rice, but I really haven't thought about it. I mean, brown rice doesn't taste as good as white rice, so I doubt people would be tempted to eat 2 cups of it a day. Regardless, I guess the question would be whether the bran on the white rice would have the effect of reducing an insulin response. I suspect it would have some effect, but I can't really make an informed comment on that.