While the daily backup system is wonderful, I think it would be helpful to allow for more frequent backups (even if it means a 2nd cron job). It'd be nice to have hourly database backups, despite the massive size, because the data is crucially important. Yes, I am aware this can be done manually with custom cron scripts, but it'd be cool to see this implemented too.
This can be achieved with the cron option flags feature: http://docs.whmcs.com/Crons#Option_Flags
To contionue your example you'd create a second cron job scheduled hourly running this command:
php -q /path/to/cron.php do_backups