Viper Backup for Windows & Mac does incremental backups (only the modified portion of your files/folders are sent to the Viper Servers).   So if your initial backup dump did not do much damage to your quota, then daily incrementals of new and changed files won't increase your usage very much at all.  Another added bonus with Viper compared to all of our competitors, is that we only tax you on your initial file, not the save versions, thereafter.  So you can enjoy unlimited versions of all saved documents for free, for life. 

For example, say you upload a 4mb Word Document.  In the next 60 days, you made 10 revisions of that document.  You will have access to each saved version, which technically takes up 20mb now.  However, Viper will only tax you for 4mb.