Well 4 heads are better than 2 aren't they? 
Just a quick off the top of my head look at your configuration makes me itch to do something different with the drive array. I'm reluctant to implement anything on Raid 0 if it's a production system where I might be forced to do a reinstall the OS in the middle of the night. Assuming you're working with 6 disks, I'd be more inclined to split this into 3 Raid 1's or one Raid 1, one Raid 5, and one hot spare.
That's really the first question to answer before you start installing. Trust me, it's a lot better to do this on the front end than trying to change it after it's built. Just my thoughts for what they're worth.
My hovercraft is full of eels.