I run GRsync on my (Linux) machine which has about 700GB of data backed up to a USB hard drive. Initial back up to a long time, but subsequent backups which only deal with changes are quick and efficient.
I realize this package is not much use to most PPRuner's but I wanted to highlight one of the best points. The data on the USB hard drive is neither compressed nor encrypted and can be accessed by mounting the drive on any Linux or Windows computer without any issues.