Perhaps, but this did not come from a requirement in the reporting module. It has introduced it’s fair share of compatibility issues in how we have used Cohort in reporting as well. In retrospect, we could ask whether we should have have made this change to Cohort, or rather have created a new Domain object (maybe a subclass) that added the ability to date constrain cohort membership and left the original Cohort class completely backwards-compatible.
Of course, if no one is actually using the new CohortMembership construct for anything in reality, maybe revisiting this is worthwhile?
Mike