Have you looked at the SeriTek 1EN2 sold by FirmTek? It is a nicely made small 2 bay SATA, hot swapable drive unite. You could set up the Seritek to mirror the drives so you are writing to two drives simultaneously for back up, then swap out 300 gig drives as they fill up. More drives would afford more protection than a single raid unite, and it would be easier to package individual drives for safe transport. The seritek set up in raid 0 also has plenty throughput for multiple channels of DVCPRO HD back in the editing suite.
Drew Harty