Let's start by asking this: you have a boatload of memory, but what do you have for storage? It'll help to know that.
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
Why would you want to make the RAM act like a disk, when you could let the RAM act like RAM and hold more data in the RAM cache?
For the After Effects global performance cache, this doesn't make any sense.
What if AE will never use the entire, say 64GB of RAM you have installed? Would creating a RAM disk for something speed up overall performance? Maybe AE itself could run from a RAM disk image (that also saves itself in case of fire)?