On my '09 Mac Pro I've been using a 120GB SSD for my scratch disk and plan to put it, along with my 250GB SSD boot drive, on a SATA III PCIe 2 controller card which splits 4 SATA channels between 2 SATA and 2 eSATA ports. My other HDs can stay on the system SATA II, which means I won't really be...