Sorting the Loop by Taxonomy Value

This doesn’t seems to be natively possible, even with upcoming improvements in WP 3.1.

[…] That’s not what taxonomies are for. Taxonomies are for grouping, not for ordering by. If you want to order by something, it has to be something in the post itself, not a term in a taxo. Otto

For this kind of data custom fields make much more sense. Instead of “group of people who weight 60kg”, it should be “Player A (60kg), Player B (60kg), etc”.

Details are by definition individual. Taxonomies are broad generic groups.