I don't think we should be banking on users downloading extra tools to get our site to work correctly, especially as the established reason IE6 still controls such a big market share is due to large institution (schools, etc) unable to upgrade

However, if we're comfortable with dropping IE6 support, we feel there's a strong benefit of using `rem`, and we're not breaking any 'laws' (http://europa.eu/geninfo/accessibility_policy_en.htm), then lets go for it