You can do displacement, the technique is not obvious.  As illustrated below, take your displacement map and plug it into a math node and set the type to multiply.  Plug the math node into the CyclesSurface.  Play with the value1 until you get a good displacement without distortions.  Use the node preview to judge how much displacement is occurring.

Ignore the Value3 on this node, it's a Cycles Math node and the Value3 is reserved for other functions.