No, moving users between COS objects isn't in the bulk edit tool - you should be able to do this in the SA. You can go to the "subscribers" link under Class Of Service in the SA and then use the "reassign" option to pick as many users as you want and move them to another COS of your choice.
Also, if you go to delete a COS (one that you've created - you can't delete the two built in COS objects that come with the system) it'll let you move all those users at once to another COS you select.
