I'm pretty sure the stufftyness of BMI shines like the sun when you get to people who work out a lot. Muscle weighs more than fat, so you might end up with a 6'1" guy who's thin but pretty buff who is overweight according to BMI. I don't consider BMI anymore.
It seems like it'd only work for slightly buff people or slightly overweight people. I don't think such a simple math equation is enough to calculate if you're healthy or not, there are a lot more factors than that.