If you want to save a little money, and gain some space, you could go with the OtherWorld Computing (OWC) 500GB Firewire RAID/Drives https://eshop.macsales.com/shop/firewire/1394/USB/EliteAL/RAID/ Maybe not quite as good as G-RAID, but a lot of bang for the buck. They've been making drives for a long time and have been a decent company to deal with.
Having said all that, right now today, I"d go with the G-tech (raid or single drive. SATA, then FireWire). However, the OWC drives are an excellent cost effective option that I wouldn't hesitate to use for backups, etc. G-Tech is probably overkill for backups unless you're planning on working off of it regularly.