I decided to go with the Drobo. It works as a JBOD raid, and you can mix and match disks and capacities. The drawback with the drobo is that it doesn't have a native networking capability. For that you need to buy a droboshare, or hook it up to a box & share it. And it has USB2, and 1394b, but not 1394a. So if you don't currently have firewire 800 capabilities, I recommend you get a card immediately if you choose to hook it up to a PC.