Adding a third doesn't always improve the performance as much as expected when it comes to SSD's mainly because at the point you are being bottlenecked by the motherboard chipset. Most motherboards are completely incapable of handling that much through put on the SATA/IDE bus. In fact, there have been reports of doing this causing some motherboards to burn out from the stress and heat generated.
I would stick with only 1 or 2 drives. If you really want more, then you need to get a PCIe card or drive as the PCIe has a bigger bus.
I would stick with only 1 or 2 drives. If you really want more, then you need to get a PCIe card or drive as the PCIe has a bigger bus.