I use an external SSD for video capture where my HDD has lagged behind but with it connected via USB 3.1 or 0 it's left something to be desired. that's also a strictly write-to situation. I'm wondering if it would be worth it (effort-wise) to do an external SSD for WoW and if there's anything I should worry about. running it off of my HDD the only issue I've really had is loading times after zoning for the first time since logging in.