A better approach would be to add another WD Black and then configure those 4 disks in two raid0 arrays. SSD's are overrated in their performance. See Adobe Forums: The SSD myth unraveled
The Sandforce controller seems to be an utter disaster when is comes to reliability and you may be lucky to achieve write speeds of 70 MB/s, far less than conventional disks, with uncompressable data like video material, if your SSD still lives. This despite their unreliable marketing claims of 500 MB/s plus.
IMO SSD's are still a no-go, even when conventional hard disks have doubled in price in the last months.