It's really depend on your luck. I've done that at several O-Stores and O-vaults. In 2010, I got a REALLY REALLY dark ruby pair with purple hues at an O-store. From my experience, O-stores have better products than O-vaults. I checked 3 vaults in the past few weeks and found only Fruby, some...
There's a thread about this in the X Metal discussion section. Here is the link http://www.oakleyforum.com/oakley-x-metal-discussion/1134-x-metal-unobtanium-interchangeable.html