What we do to figure this out, is in Report Services going under the reporting group of 'Transaction Log Reports' --> 'Document and Folder History Transactions'. In this report I grab the action of 'Viewed Document' and the user group the epic users are added to in our case it is "ALL EPIC USERS". You could always run this report in the client as well but I like that with report services you can save as an excel file.
For OnBase downtime we try and schedule during a time frame that appears to have an average low number of views but when it is down we have no clever way of viewing the documents. But I would be interested to hear if someone else does.
