As you said its very true,Snapshots are ideal for scenarios like auditing,reporting etc.I am not quite clear with the statement that "If the snapshot is allowed to run for weeks".You mean to say that if we keep taking snapshots daily for a week or so.It would be a overhead on the server if the database undeergoes frequent changes.Otherwise,if the database is quite static,then it wouldnt be a overhead.
Regards,
S.Srivathsani