I've taken a brief look at 3.7beta2 and the implementation of project roles looks to provide the long awaited functionality that gives project admins the ability to add / remove project members. It appears that the Admin-> Send Email function still only allows groups to be used for recipents - this should also handle project roles. So currently migrating from groups to project roles would allow you to remove grouping altogether. Not sure whether other functions are dependent on groups aswell.