A RAID0 of some 128GB SSDs is faster than this for small block sizes. And you should be able to fuse this with an external (RAID of) hard drives via FW800 as well.
Also, a 2009 Mac Mini doesn't have internal SATA-III, it's SATA-II, but you can always do the eSATA mod to route out something faster than 1GBit/s.
YEAH I posted a long thread on this site on how to do that mod. I actually have all the parts in my parts drawer. I still think he should return the gear he purchased sell the old mini on ebay and get newer stuff.