So, aside from the internal 1TB PCIE SSD, I've got a pair of TB2 Lacie Little Big Disks in a RAID 0 configuration, and a Mercury Helios with a 480GB PCIE SSD.
In addition (a holdover from my old system, but still totally useful for long-term storage), I've got a pair of eSATA 4-drive HDD raids, each in a RAID 5 configuration.
Long story short, I've gone all out for speed, with enough capacity to hold any one project on the fastest drives (the LBD). That said, nothing is going to match the 4+GB/s of the RAM Disk. The LBD pair tops out at about 2200MB/s