FireMax drives (from proMax)
I recently bought a 1 TB fireMAX from proMAX, and it's working fine. These guys have excellent support BTW, as well as a 3 year warranty.
It supports FW400, FW800 and USB 2.0 and comes in various sizes. It ships as a RAID 1, but like you, I wanted redundancy over capacity and performance, so I pulled the jumper to convert it from a 1 TB RAID 1 stripe array to a 500 GB RAID 0 mirror array (the unit actually contains two 500 GB drives internally).
Although this configuration will survive a single drive failure w/o loss of data, there's still some risk for catastrophic failure, as both drives are contained within the same enclosure (i.e. two physically separated mirrored drives would provide additional protection against data loss).
As an added benefit, the style of this drive matches perfectly with a powermac/mac Pro case.
BTW - I bought a 60 GB external FW drive from this company about five years ago, and it's still working fine, and I just received a 400 GB drive from them last week to be used with Time Machine.
Here's the link if interested:
http://www2.promax.com/Products/Dual-Combo
Good luck...