I was thinking you'd use the Voyager dock for your backup drive(s), and put that extra SSD in the lower ODD bay.Brilliant!! Ok so I'll get the CalDigit FASTA-6GU3 card ($139 OWC: http://eshop.macsales.com/item/CalDigit/FASTA6GU3/ ) and the Voyager Q dock!!
So I'll have bay 1 SSD 400GB boot drive (250MB/sec), bay 2 SSD 400GB (250MB/sec), bay 3 & 4 two 2TB HDDs in RAID 0 (215MB/sec) and the voyager q dock with another SSD 256GB (500+MB/sec). How would you allocate these drives for optimal performance with final cut pro x? 1 SSD boot drive, 1 SSD project data, 1 SSD scratch disk, 2 HDD in Raid 0 as export volume??
I've heard using an SSD for scratch media is very hard on it, and I've also heard it's no different than normal use. Just thought I'd mention that so you can at least look into it yourself and decide. I use a 2x2TB HDD RAID 0 for my general scratch files, and also use my RAID 6 for previews and scratch specifically in Premiere, but I have that luxury.
I'd use one SSD for boot, second SSD for FCP project files, exports, scratch and preview files, and the 2x2TB HDD RAID 0 for media. Then back up on the 4TB whenever you cross a major milestone, or nightly, whichever comes first.