Apologies for not getting back to this sooner...
I'll be honest, I didn't see a big improvement while taking a 5-man team to Orgrimmar on Illidan during peak hours and unless you really just want a RAM drive to have a RAM drive... I'd say a current gen SSD paired up with a nice beefy CPU/GPU will net you very similar results.
I wanted to see if a 10-man team would benefit more from the drive, but I couldn't take all 10 to Orgrimmar without having a few random instances crash due to running out of memory (what was left of it after the RAM drive). Oh well...
As others in the thread have shown, using free software can be a little more tedious getting the RAM drive all setup and working, but once it works it works. If you're willing to dish out $50 for a 2 PC lifetime license from Romex Software for Primo Ramdisk, you can do all kinds of crazy things with it. I say $50 because the $20 Standard Edition license only lets you create a drive with a maximum size of 8GB so you're forced to kick it up to the Professional Edition for a 32GB max.
I'm obviously no expert in this field, and I'm sure you can accomplish the same thing with free software if you're willing to work with it, but Primo Ramdisk seemed to offer the best overall package with a very nice GUI. It has a fully functional free 30-day trial that I used to conduct the testing that I did.
Should take about a minute to move the entire folder into the RAM drive from an SSD hooked up via SATAIII.