OT: Reliable Scratch Disk Recommendation

Want to buy a new disk (500GB? 1TB?) to use exclusively with FCP as the scratch disk.
Would appreciate any recommendation for a fast, reliable disk (FireWire 800).
Am using G-Raids currently (several years old) and want to get a new external HD.

Regards, Cyrus
iMac 27" Intel i7 Quad-Core; 16GB RAM; 2TB HD
Final Cut Studio, FCP X, Photoshop CS5, After Effects, etc.

My "Scratch Disk":

[www.caldigit.com]

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