An update on my Crashplan purchase.
I don't have a great ADSL connection here, so the first Crashplan sync took about a week - during that time our Internet slowed to a crawl. Crashplan does have a sleep mode, so I was able to use that mode when a faster Internet was needed.
The system seems straight forward, although some understanding of the computer files & folders is useful, it is not essential as Crashplan auto selects the current User profile. One slight thing is that it includes the hidden Application Data directory & therefore the browser cache. There is no way within the Application Folder to select or deselect subfolders as there is with regular folders, so I am maintaining backups of a number of temporary folders without much purpose. There is an option for filename exclusions, so I may look at that.