Change profile type on change of Joomla user group

Wondering if it is possible to change ES's profile type automatically based on a change in a users Joomla user group. I've got a membership site and working on some changes which include an already existing phpBB board/membership system with Joomla,ES, an a couple other Joomla components. One hurdle is that registered users are either active with a subscription or have an expired subscription and Joomla usergroups are changing accordingly. I'd like for ES to automatically detect a change in the Joomla user group in order to change their profile type and the only way I can see it occurring is if I create a cron script unless I'm missing some other way of doing so. Any suggestions?
thanks.