http://www.lightstalkers.org/need-help-in-building-a-redundant-storage-device
i just realized you contributed to that old post.
i am enjoying my pc with built in raid array, as i just got a new laptop i am going to install bsd on the pc and set it up as a dedicated file server.
i think peoples bashing of usb2 is unmerited, its really damn fast.
granted it might have slightly slower response times and slower rates for multiple files but it is still way more then useable. especially if you are just looking for storage.
you won’t actually be working out of the drobo, just storing files on it and grabbing the odd one for editing.
if you were going to run a web server from a drobo i would recommend something else but it makes perfect sense for file storage.
a good deal of these technologies are just marketing buzz, think about what you really need.