It may not compare to the io-Drive, but DDrdrive's X1 still packs a punch in terms of speed and price.
Unlike other SSDs, the X1 utilises two types of memory—4GB DRAM and 4GB NAND aligned on a PCIe card. Because RAM can be volatile, the NAND kicks in and safely backs up the information. According to a PC Perspective review, the drive features "single sector IOPS (input/output operations per second) unmatched by any other device available" and has the benefit of a IOPS cost that is about 1/5 of the io-Drive.
So, essentially you are getting a lot of bang for your buck here—but at the end of the day you are still talking $US1495 for a drive with 4GB capacity. Obviously, that means the majority of us will have to wait a while longer to experience this kind of performance. [DDRdrive and CNET and PC Perspective]