Arriving today is a NAS that will have about 20TB capacity. I'm going to set up nightly FTP transfers of *SAVF files from the IBM i partition over to these drives and use them as backup. I've been desiring this kind of thing for a while, but capacity and cost have just come into line with what's practical. The drives are RAID'd and in another physical location, and I don't really care how long the transfer takes, but it shouldn't be too bad at 100MBs LAN speeds. (Yes we have a GB LAN but the weakest link is a 100MB CiSCO ASA).
I want to do this for a client as well, but outbound T1 lines or cable connectivity can take "centuries" even at 10MB (most are 1.5 to 3.0 MB). So I don't think the networking has come into play yet.
What are you doing for off-site backups?