TFTP??? Not only does FTP not encrypt passwords, TFTP has absolutely NO security. Not really the best choice for transfering company files to an off site location. Also RAID isn't going to bring back your files in the event of building fire, flood, or some other act of god.
If your going to do an online backup solution http://www.usdatatrust.com
would be a good choice. They have an install client and all your data is transfered securely.
If your needs are simple, just use a simple solution. No need to over complicate a simple task.