From doing some basic testing so far here between the ARC-1280ML (IOP341 @ 800Mhz) and the ARC-1680ix-24 (IOP348 @ 1.2Ghz) on a raid-6 array of 24 1TB ST1000340NS drives, I've found that the ARC-1280ML is actually a little faster in performance (random IOPS & Streaming) (about 5% or so) than the 1680ix card. I didn't have the time to run a full gamut of tests that I would have liked though so at this point take it with a grain of salt. If anything the numbers were within statistical error.