If the two IO benchmarks are *that* far apart, there is something seriously wrong with the test. Mostly likely, one of the tests is reading the same data blocks over and over, and the blocks are being stored in cache (either on the disk, in the array, or on the OS). What type of interface attaches the drives? If it's a 4x SAS connection, then the max theoretical bandwidth is 1200MB/sec.
Beyond that, using the word "sequential" with SSDs makes no sense because the internal bits aren't stored sequentially as they are on a hard disk. Perhaps you meant "read performance".