Yes Richard,
I found out more about this as I looked into it. Nevertheless, it would still make a plausible solution for having a SCSI based RAID Stripe set internally. However, I am looking into several different SCSI controllers to see about solutions with larger data buffers.
Compared to an xServe RAID running SATA disks, a SCSI raid will always have faster disk seek times but it's a matter of eliminating the controller bottleneck. Obviously this is the advantage of the xServeRAID but I would prefer to find a way to have an encapsulated single machine solution for doing HD files.

Give me your feedback on the use of internal SCSI Raids and what cards you've used. Have you tried a 4 disk stripe or just a typical 2 disk stripe?
One thought is to use two SCSI controllers that will do hardware striping and then use OSX to perform a software stripe across two controllers.